Executive Summary:
A critical use-after-free vulnerability, identified as CVE-2026-0884, exists within the JavaScript Engine of certain products, including Mozilla Firefox. Successful exploitation could allow a remote attacker to execute arbitrary code on a victim's system by tricking them into visiting a specially crafted webpage, potentially leading to a full system compromise. Due to its critical severity rating (CVSS 9.8), immediate remediation is strongly advised.

Vulnerability Details

CVE-ID: CVE-2026-0884

Affected Software: Mozilla Firefox, Mozilla Firefox ESR

Affected Versions: Firefox versions prior to 147 and Firefox ESR versions prior to 140.7

Vulnerability: This is a use-after-free vulnerability in the JavaScript Engine. A use-after-free (UAF) condition occurs when a program continues to use a pointer to a memory location after that memory has been deallocated or "freed." An attacker can exploit this by crafting a malicious webpage with specific JavaScript code that triggers this condition. By manipulating the freed memory space before it is used again, an attacker can corrupt memory in a controlled way, leading to a crash or, more severely, the execution of arbitrary code with the permissions of the user running the browser.

Business Impact

This vulnerability is rated as critical severity with a CVSS score of 9.8. A successful exploit could have a severe impact on the business, leading to a complete compromise of an affected user's workstation. Potential consequences include the theft of sensitive data such as credentials and corporate information, the deployment of malware like ransomware or spyware, and the use of the compromised system as a foothold to launch further attacks against the internal network. Such an incident could result in significant financial loss, reputational damage, and operational disruption.

Remediation Plan

Immediate Action: The primary remediation is to apply the security updates provided by the vendor. Administrators should update Mozilla Firefox to version 147 or later and Mozilla Firefox ESR to version 140.7 or later. Until patching is complete, actively monitor for signs of exploitation by reviewing endpoint and network logs for anomalous activity originating from browser processes.

Proactive Monitoring: Implement enhanced monitoring on endpoint detection and response (EDR) solutions for suspicious behavior related to browser processes. This includes looking for browsers spawning child processes like cmd.exe or powershell.exe, unusual network connections to unknown domains, or alerts related to memory corruption exploit techniques. Review web proxy and DNS logs for traffic to newly registered or known malicious domains.

Compensating Controls: If immediate patching is not feasible, consider the following compensating controls:

• Enforce the use of an alternative, non-vulnerable web browser for accessing untrusted websites.
• Utilize web filtering and email security gateways to block access to malicious or suspicious websites.
• Ensure endpoint security solutions (Antivirus, EDR) are up-to-date and configured to detect and block common exploit techniques.
• Restrict user permissions to limit the impact of a successful code execution exploit.

Exploitation Status

Public Exploit Available: False

Analyst Notes: As of January 13, 2026, there are no known public exploits available for this vulnerability. However, vulnerabilities of this type and severity in widely-used software like web browsers are prime targets for threat actors. It is highly probable that proof-of-concept code and active exploitation will emerge. This vulnerability is not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog.

Analyst Recommendation

Given the critical CVSS score of 9.8 and the high potential for remote code execution, immediate action is required. We strongly recommend that organizations prioritize the deployment of the necessary security updates to all systems running vulnerable versions of Firefox and Firefox ESR. Due to the high likelihood of future exploitation, all vulnerable instances should be considered at significant risk. If patching cannot be performed immediately, implement the suggested compensating controls and maintain a heightened state of monitoring until all systems are secured.

Executive Summary:
A critical vulnerability has been discovered in the Graphics component of multiple Mozilla Firefox products. This flaw, resulting from incorrect boundary conditions, allows a remote attacker to bypass the browser's security sandbox by tricking a user into visiting a malicious webpage, potentially leading to arbitrary code execution on the user's system and a full compromise of the machine.

Vulnerability Details

CVE-ID: CVE-2026-0879

Affected Software: Mozilla Firefox, Mozilla Firefox ESR

Affected Versions:

• Firefox < 147
• Firefox ESR < 115.32
• Firefox ESR < 140.7

Vulnerability:
This vulnerability is a sandbox escape caused by a flaw in how the browser's Graphics component handles boundary conditions. An attacker can exploit this by crafting a malicious webpage with specially designed graphical content. When a user with a vulnerable version of Firefox visits this page, the flawed code processes the content incorrectly, leading to a memory corruption error that allows the attacker to write data outside of its intended memory buffer. This can be leveraged to execute arbitrary code, escaping the browser's sandbox and gaining control over the underlying operating system with the permissions of the logged-in user.

Business Impact

This vulnerability is rated as critical severity with a CVSS score of 9.8, posing a significant risk to the organization. Successful exploitation could lead to a complete compromise of an endpoint system, allowing an attacker to install malware (such as ransomware or spyware), steal sensitive corporate data, capture user credentials, or use the compromised machine as a pivot point to move laterally within the network. The potential consequences include major data breaches, financial loss, operational disruption, and significant reputational damage.

Remediation Plan

Immediate Action:
Immediately update all affected Mozilla Firefox and Firefox ESR installations to the latest patched versions (Firefox 147, Firefox ESR 115.32, Firefox ESR 140.7, or later). Following the update, monitor endpoints for any signs of exploitation attempts by reviewing security logs for anomalous activity originating from browser processes.

Proactive Monitoring:

• Monitor Endpoint Detection and Response (EDR) logs for suspicious child processes being spawned by firefox.exe (e.g., cmd.exe, powershell.exe).
• Analyze network traffic for unusual outbound connections from workstations to unknown or malicious IP addresses.
• Review system logs for unexpected file creation, modification, or registry changes originating from the browser.

Compensating Controls:
If immediate patching is not feasible, implement the following controls:

• Use application control solutions to prevent browsers from launching unauthorized executables.
• Ensure web filtering and DNS security are in place to block access to uncategorized or known malicious websites.
• Confirm that endpoint antivirus and EDR solutions are up-to-date and configured to detect and block memory exploitation techniques.

Exploitation Status

Public Exploit Available: false

Analyst Notes:
As of Jan 13, 2026, there is no known public proof-of-concept exploit code available for this vulnerability. This CVE is not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog, suggesting there is no evidence of widespread active exploitation. However, due to the critical nature of browser sandbox escapes, it is highly probable that threat actors will prioritize developing an exploit.

Analyst Recommendation

Given the critical CVSS score of 9.8 and the potential for complete system compromise via a common attack vector (web browsing), it is imperative that organizations treat this vulnerability with the highest priority. The absence of a CISA KEV listing should not reduce the urgency. We strongly recommend that all vulnerable Firefox installations are patched immediately to mitigate the risk of data breaches and malware infections.

Executive Summary:
A collection of high-severity memory safety vulnerabilities has been identified in Mozilla Firefox, impacting multiple products. Successful exploitation could allow a remote attacker to execute arbitrary code on a user's system simply by tricking them into visiting a malicious webpage, potentially leading to a full system compromise.

Vulnerability Details

CVE-ID: CVE-2025-8040

Affected Software: Firefox Multiple Products

Affected Versions: Firefox ESR 140. See vendor advisory for a complete list of specific affected versions.

Vulnerability: This CVE represents a collection of memory safety bugs, such as buffer overflows or use-after-free errors, within the Firefox browser engine. An attacker can exploit these flaws by crafting a malicious webpage with specific content (e.g., JavaScript, WebAssembly). When a user with a vulnerable version of Firefox visits this page, the browser's memory can be corrupted in a way that allows the attacker to execute arbitrary code with the same permissions as the logged-in user.

Business Impact

This vulnerability is rated as High severity with a CVSS score of 8.8, posing a significant risk to the organization. A successful exploit could lead to a complete compromise of the affected endpoint, resulting in data theft of sensitive corporate or personal information, credential harvesting, and the deployment of additional malware like ransomware or spyware. The compromised system could also be used as a pivot point to launch further attacks against the internal network, leading to potential data breaches, financial loss, and severe reputational damage.

Remediation Plan

Immediate Action: The primary remediation is to apply the security updates provided by Mozilla to all affected Firefox and Firefox ESR installations across the organization without delay. After patching, system administrators should monitor for any signs of post-exploitation activity and review web proxy and endpoint logs for connections to suspicious domains that may have occurred prior to the update.

Proactive Monitoring: Implement enhanced monitoring on endpoints and network traffic. Look for unusual outbound connections from Firefox processes, unexpected browser crashes, or the creation of suspicious files or processes spawned by Firefox. Endpoint Detection and Response (EDR) solutions should be configured to alert on these behaviors.

Compensating Controls: If immediate patching is not feasible, organizations should consider temporary compensating controls. This includes enforcing the use of script-blocking browser extensions, ensuring users do not have local administrator privileges, and utilizing web filtering solutions to block access to uncategorized or known malicious websites.

Exploitation Status

Public Exploit Available: false

Analyst Notes: As of July 23, 2025, there are no known public exploits specifically for CVE-2025-8040. However, memory safety vulnerabilities in widely used web browsers are highly valuable to threat actors and are often exploited before public details become available. The vulnerability is not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog.

Analyst Recommendation

Given the high severity (CVSS 8.8) and the potential for remote code execution through a common attack vector (web browsing), this vulnerability requires immediate attention. We strongly recommend that all organizations prioritize the deployment of the vendor-supplied patches for all affected Firefox products. Although not yet listed in the CISA KEV catalog, the nature of this vulnerability makes it a prime target for exploitation, and it should be treated with the highest urgency to prevent potential system compromise and data breaches.

Executive Summary:
A collection of high-severity memory safety vulnerabilities has been identified in Mozilla Firefox ESR. A remote attacker could exploit these bugs by tricking a user into visiting a specially crafted webpage, which could lead to arbitrary code execution and a full compromise of the affected system. Organizations should treat this as a critical threat and apply security updates immediately to prevent potential data theft, malware installation, or further network intrusion.

Vulnerability Details

CVE-ID: CVE-2025-8035

Affected Software: Firefox Multiple Products

Affected Versions: Firefox ESR versions prior to 128.1. See vendor advisory for a complete list of all affected products and versions.

Vulnerability: This CVE represents a collection of memory safety bugs, such as use-after-free or buffer overflow vulnerabilities. An attacker can exploit these flaws by creating a malicious website containing specific web content (e.g., JavaScript, WebAssembly). When a user navigates to this malicious site using a vulnerable version of Firefox, the browser's memory can be corrupted, allowing the attacker to execute arbitrary code on the victim's machine with the same permissions as the logged-in user.

Business Impact

This vulnerability is rated as High severity with a CVSS score of 8.8. Successful exploitation poses a significant risk to the organization, as it could lead to a complete compromise of an endpoint. Potential consequences include the theft of sensitive corporate data, financial information, or user credentials; the installation of persistent malware like ransomware or spyware; and the use of the compromised machine as a pivot point for lateral movement within the corporate network. These outcomes could result in significant financial loss, operational disruption, and reputational damage.

Remediation Plan

Immediate Action: The primary remediation is to apply the security updates provided by the vendor across all affected systems immediately. System administrators should ensure that all instances of Firefox and Firefox ESR are updated to a patched version (e.g., Firefox ESR 128.1 or later). Following the update, monitor endpoints for any signs of post-exploitation activity and review access logs for unusual patterns originating from user workstations.

Proactive Monitoring: Security teams should proactively monitor for potential exploitation attempts. This includes analyzing network traffic for connections to unknown or suspicious domains, inspecting endpoint logs for unusual process creation originating from firefox.exe (e.g., cmd.exe, powershell.exe), and monitoring DNS queries for anomalous requests.

Compensating Controls: If immediate patching is not feasible, implement the following compensating controls:

• Utilize a secure web gateway or web proxy to block access to uncategorized or known malicious websites.
• Enforce application control policies to prevent Firefox from launching unauthorized child processes.
• Ensure Endpoint Detection and Response (EDR) and antivirus solutions are up-to-date and configured for behavioral-based threat detection.
• Conduct user awareness training to reinforce caution against clicking suspicious links in emails or on websites.

Exploitation Status

Public Exploit Available: false

Analyst Notes: As of July 23, 2025, there are no known public proof-of-concept exploits for this vulnerability, and it is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog. However, memory corruption vulnerabilities in widely used web browsers are highly attractive targets for threat actors, who often reverse-engineer patches to develop exploits rapidly.

Analyst Recommendation
Given the High severity (CVSS 8.8) and the potential for remote code execution, this vulnerability presents a critical risk to the organization. We strongly recommend that all available security updates from Mozilla are deployed as an immediate priority. Although exploitation requires user interaction, this is a low barrier for attackers using common phishing or malvertising techniques. The absence of a CISA KEV entry should not be interpreted as a low risk; organizations must act preemptively to mitigate this threat before active exploitation is observed in the wild.

Executive Summary:
A high-severity vulnerability, identified as CVE-2025-8034, has been discovered in Mozilla Firefox, originating from memory safety bugs. Successful exploitation could allow a remote attacker to execute arbitrary code on a user's system by tricking them into visiting a malicious website, potentially leading to a full system compromise and data theft.

Vulnerability Details

CVE-ID: CVE-2025-8034

Affected Software: Firefox Multiple Products

Affected Versions: Firefox ESR 115. See vendor advisory for a complete list of specific affected versions.

Vulnerability: This vulnerability encompasses a collection of memory safety bugs, such as buffer overflows or use-after-free errors, within the Firefox browser engine. An attacker can exploit these flaws by crafting a malicious webpage with specific web content (e.g., JavaScript, WebAssembly) designed to trigger memory corruption. When a user with an affected Firefox version visits this page, the corrupted memory state can be manipulated by the attacker to execute arbitrary code with the privileges of the logged-in user.

Business Impact

This vulnerability is rated as High severity with a CVSS score of 8.8, posing a significant risk to the organization. Successful exploitation could lead to the complete compromise of employee workstations, enabling attackers to steal sensitive data, including login credentials, financial information, and proprietary corporate documents. Furthermore, a compromised endpoint can serve as a beachhead for attackers to move laterally across the network, install persistent malware like ransomware or spyware, and disrupt business operations, leading to financial loss and reputational damage.

Remediation Plan

Immediate Action: The primary remediation is to apply the security updates provided by Mozilla across all affected endpoints immediately. System administrators should use centralized software deployment tools to ensure the patch for Firefox and Firefox ESR is deployed promptly and universally. Concurrently, security teams should begin actively monitoring for indicators of compromise related to this vulnerability.

Proactive Monitoring: Security teams should monitor for signs of exploitation. This includes reviewing endpoint logs for unusual child processes spawning from firefox.exe, analyzing DNS logs for requests to newly registered or known malicious domains, and inspecting network traffic for anomalous outbound connections from workstations. EDR and SIEM alerts should be configured to detect suspicious browser process behavior.

Compensating Controls: If immediate patching is not feasible, organizations should implement compensating controls. Enforce strict web filtering to block access to uncategorized and known malicious websites. Ensure users operate under the principle of least privilege and do not run web browsers with administrative rights. Heighten user awareness by communicating the risk and advising caution when clicking links or visiting unfamiliar websites.

Exploitation Status

Public Exploit Available: false

Analyst Notes: As of July 23, 2025, there is no known public proof-of-concept exploit, and the vulnerability is not reported to be actively exploited in the wild. However, memory safety vulnerabilities in major web browsers are prime targets for exploit development by threat actors. It is anticipated that exploit code could become public or integrated into exploit kits in the near future. This vulnerability is not currently listed in CISA's Known Exploited Vulnerabilities (KEV) catalog.

Analyst Recommendation
Given the high severity (CVSS 8.8) and the potential for remote code execution, this vulnerability presents a critical risk to the organization. We strongly recommend that all system administrators prioritize the immediate deployment of the vendor-supplied patches for all versions of Firefox. While there is no current evidence of active exploitation, the widespread use of Firefox makes it an attractive target, and proactive patching is the most effective defense to prevent future compromise.

Executive Summary:
A critical memory safety vulnerability, identified as CVE-2025-11721, has been discovered in Mozilla Firefox and Thunderbird. This flaw could allow a remote attacker to execute arbitrary code on a user's system by tricking them into visiting a malicious website, potentially leading to a full system compromise. Due to its critical severity (CVSS 9.8), immediate patching is required to prevent potential exploitation.

Vulnerability Details

CVE-ID: CVE-2025-11721

Affected Software: Memory safety bug present in Firefox Multiple Products

Affected Versions: Firefox 143 and Thunderbird 143

Vulnerability: The vulnerability is a memory safety bug within the browser and email client's engine. An attacker can exploit this by crafting a malicious webpage or email containing specially designed content. When a user navigates to this page with an affected browser or opens the email in the affected client, the bug is triggered, leading to memory corruption. This corruption can be leveraged by the attacker to bypass security mechanisms and execute arbitrary code with the privileges of the logged-in user.

Business Impact

This vulnerability presents a critical risk to the organization, reflected by its CVSS score of 9.8. Successful exploitation would grant an attacker complete control over an affected endpoint, allowing for the installation of malware (such as ransomware or spyware), theft of sensitive data, and lateral movement within the corporate network. Given the widespread use of Firefox and Thunderbird in enterprise environments, a successful attack could lead to significant data breaches, financial loss, and severe reputational damage.

Remediation Plan

Immediate Action: Update Memory safety bug present in Firefox Multiple Products to the latest version. Check vendor security advisory for specific patch details. Monitor for exploitation attempts and review access logs.

Proactive Monitoring: Security teams should monitor for unusual outbound network traffic from workstations, especially connections to unknown or suspicious domains originating from firefox.exe or thunderbird.exe processes. Endpoint Detection and Response (EDR) systems should be configured to alert on anomalous process creation, such as a browser process spawning a command shell (cmd.exe, powershell.exe) or other unexpected executables.

Compensating Controls: If immediate patching is not feasible, consider implementing temporary compensating controls. These include restricting web browsing to a list of trusted sites via a web proxy, enabling advanced memory protection features in endpoint security solutions, and ensuring users do not operate with administrative privileges for daily tasks. Additionally, disabling JavaScript on untrusted websites can reduce the attack surface, though this may impact site functionality.

Exploitation Status

Public Exploit Available: false

Analyst Notes: As of October 14, 2025, there is no known public proof-of-concept exploit code available for this vulnerability. The vendor's advisory notes that the bug shows evidence of memory corruption that could be exploited, but there are no reports of active exploitation in the wild. This vulnerability is not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog.

Analyst Recommendation

Given the critical severity (CVSS 9.8) and the potential for remote code execution, we strongly recommend that organizations prioritize the immediate deployment of the security updates provided by Mozilla. Although there is no evidence of active exploitation at this time, browser vulnerabilities are highly attractive targets for threat actors, and exploit code can be developed rapidly. All systems running the affected versions of Firefox and Thunderbird should be patched without delay to mitigate the risk of a full system compromise.

Executive Summary:
A critical vulnerability has been identified in Mozilla Firefox and potentially other products, assigned CVE-2025-11710 with a CVSS score of 9.8. This flaw allows a compromised or malicious web process to send specially crafted messages that trick the main, privileged browser process into leaking sensitive memory. Successful exploitation could lead to the exposure of confidential information such as passwords, session tokens, and other private data stored in the browser's memory, posing a significant risk of data breach and system compromise.

Vulnerability Details

CVE-ID: CVE-2025-11710

Affected Software: Mozilla Firefox

Affected Versions: See vendor advisory for specific affected versions

Vulnerability: The vulnerability exists in the Inter-Process Communication (IPC) mechanism between the sandboxed web content processes and the main, privileged browser process. Modern browsers use this multi-process architecture to isolate web content and enhance security. An attacker who can control a web process (e.g., by luring a user to a malicious website) can send malformed IPC messages to the main browser process. Due to improper validation of these messages, the privileged process can be forced to read from arbitrary locations in its own memory and return the data to the attacker-controlled process, effectively bypassing sandbox protections and leading to a significant information disclosure.

Business Impact

This vulnerability is rated as critical severity with a CVSS score of 9.8, indicating a high risk to the organization. Exploitation could lead to the theft of highly sensitive data processed by the browser, including user credentials, session cookies for corporate applications, personally identifiable information (PII), and financial data. This could result in unauthorized access to internal systems, data breaches, financial fraud, and significant reputational damage. The low complexity of the attack means that simply visiting a specially crafted webpage could trigger the vulnerability, making it a widespread and severe threat.

Remediation Plan

Immediate Action: Update Mozilla Firefox and any other affected products to the latest version immediately. The vendor has released patches that address this vulnerability. Ensure that all endpoints, including servers and workstations, have the update applied through automated patch management systems.

Proactive Monitoring: Monitor for signs of exploitation, which may include unexpected browser crashes, anomalous process behavior from browser child processes, or unusual outbound network traffic from endpoints. Review endpoint detection and response (EDR) logs for alerts related to memory scraping or sandbox escape attempts originating from browser processes.

Compensating Controls: If immediate patching is not feasible, consider implementing compensating controls such as deploying network-level web filtering to block access to known malicious or uncategorized websites. Ensure that EDR solutions are configured to detect and block memory protection violations and suspicious inter-process communication. Reinforce user awareness training regarding phishing and suspicious links.

Exploitation Status

Public Exploit Available: false

Analyst Notes: As of the publication date, Oct 14, 2025, there are no known public proof-of-concept exploits or active attacks leveraging this vulnerability. However, given the critical severity and the nature of the flaw (sandbox escape/information disclosure), it is highly probable that threat actors will prioritize developing exploits. Organizations should assume that exploitation is imminent.

Analyst Recommendation

This vulnerability represents a severe and immediate threat to the organization. Due to the critical CVSS score of 9.8, immediate and decisive action is required. We strongly recommend prioritizing the deployment of vendor-supplied patches to all affected systems without delay. Although this CVE is not currently listed on the CISA KEV list, its high severity makes it a likely candidate for future inclusion. All systems running vulnerable versions of the software should be considered at high risk of compromise.

Executive Summary:
A high-severity vulnerability has been discovered in the Mozilla Firefox web browser that could allow a remote attacker to execute arbitrary code on a user's system. Successful exploitation requires a user to visit a specially crafted, malicious webpage, which could lead to a full system compromise, data theft, or the installation of malware. Due to the critical nature of this flaw and the browser's role as a primary gateway to the internet, immediate patching is essential to mitigate significant security risks.

Vulnerability Details

CVE-ID: CVE-2025-11152

Affected Software: This Multiple Products (specifically Mozilla Firefox)

Affected Versions: All versions of Mozilla Firefox prior to 143.

Vulnerability: This vulnerability is a use-after-free condition within the browser's rendering engine. An attacker can create a malicious webpage with specific HTML and JavaScript elements that, when processed by an affected browser version, cause the engine to incorrectly handle memory pointers for certain objects. By manipulating these dangling pointers, an attacker can corrupt memory in a controlled way, ultimately leading to arbitrary code execution in the security context of the logged-in user.

Business Impact

This vulnerability is rated as High severity with a CVSS score of 8.6. Exploitation could have a severe impact on the organization by allowing an attacker to gain an initial foothold into the corporate network through an employee's workstation. Potential consequences include the deployment of ransomware, theft of sensitive corporate data and user credentials, installation of spyware to monitor user activity, and the ability for an attacker to pivot to other internal systems. A successful attack could result in significant financial loss, reputational damage, and operational disruption.

Remediation Plan

Immediate Action: The primary remediation is to apply vendor-supplied security updates immediately. All instances of Mozilla Firefox on corporate endpoints must be updated to version 143 or later. Following the update, security teams should actively monitor for any signs of post-patch exploitation attempts and review web proxy and endpoint logs for indicators of compromise.

Proactive Monitoring: Security teams should monitor for unusual activity originating from browser processes. This includes looking for firefox.exe spawning child processes like cmd.exe or powershell.exe, unexpected outbound network connections from workstations to unknown IP addresses, and alerts from Endpoint Detection and Response (EDR) systems related to memory corruption or browser exploitation techniques.

Compensating Controls: If immediate patching is not feasible, the following compensating controls can reduce the risk:

• Enforce the use of an alternative, fully patched web browser for accessing untrusted external websites.
• Utilize web filtering and DNS security solutions to block access to known malicious domains and uncategorized websites.
• Ensure EDR and antivirus solutions are running with up-to-date signatures and behavioral detection capabilities enabled to detect and block exploit payloads.

Exploitation Status

Public Exploit Available: False

Analyst Notes: As of October 1, 2025, there is no publicly available exploit code, and this vulnerability is not known to be actively exploited in the wild. However, given the high severity and the common targeting of browser vulnerabilities, it is highly probable that threat actors and security researchers will develop a functional exploit in the near future.

Analyst Recommendation

This vulnerability represents a critical risk to the organization. Web browsers are a direct and frequent point of interaction with external, untrusted content, making them a primary target for attackers. Although this CVE is not currently listed on the CISA KEV catalog, its high CVSS score and potential for remote code execution warrant immediate attention. We strongly recommend that all system administrators prioritize the deployment of the security update for Mozilla Firefox version 143 across all corporate assets without delay.

Executive Summary:
A high-severity vulnerability has been discovered in Mozilla Firefox and Firefox ESR, which could allow a remote attacker to execute arbitrary code on a user's system. Successful exploitation occurs if a user visits a specially crafted, malicious webpage, potentially leading to a full system compromise. This could result in data theft, malware installation, or further network intrusion.

Vulnerability Details

CVE-ID: CVE-2025-10536

Affected Software: Mozilla Firefox, Mozilla Firefox ESR

Affected Versions:

• Firefox versions prior to 143
• Firefox ESR versions prior to 140

Vulnerability:
The vulnerability is a use-after-free condition within the browser's Just-In-Time (JIT) compiler component. An attacker can exploit this by creating a malicious webpage with specific JavaScript code that manipulates memory objects in a way that triggers the flaw. When a user running a vulnerable version of Firefox navigates to this page, the browser can be tricked into executing arbitrary code with the privileges of the logged-in user, leading to a sandbox escape and full compromise of the host machine.

Business Impact

This vulnerability is rated as High severity with a CVSS score of 8.4. Exploitation could have a significant negative impact on the organization. If an employee's workstation is compromised, an attacker could exfiltrate sensitive corporate data, install persistent malware like ransomware or spyware, or use the compromised machine as a beachhead to launch further attacks against the internal network. The wide deployment of Firefox in enterprise environments makes this a critical threat that could lead to financial loss, reputational damage, and operational disruption.

Remediation Plan

Immediate Action:
Organizations must immediately apply security updates provided by Mozilla. All instances of Firefox should be updated to version 143 or later, and all instances of Firefox ESR should be updated to version 140 or later. System administrators should verify the successful deployment of these patches across all endpoints.

Proactive Monitoring:
Security teams should actively monitor for signs of exploitation. This includes scrutinizing endpoint security logs for anomalous processes spawned by firefox.exe, monitoring outbound network traffic from workstations for connections to suspicious or newly registered domains, and reviewing web proxy and DNS logs for unusual patterns. Endpoint Detection and Response (EDR) systems should be configured to alert on common memory exploitation techniques.

Compensating Controls:
If immediate patching is not feasible, the following controls can help mitigate risk:

• Utilize a secure web gateway or DNS filtering service to block access to malicious and uncategorized websites.
• Ensure EDR solutions are properly configured to detect and block browser-based exploits.
• Enforce the principle of least privilege for user accounts to limit the post-exploitation impact.
• Consider deploying browser isolation technology to execute web sessions in a secure, remote environment.

Exploitation Status

Public Exploit Available: false

Analyst Notes:
As of September 16, 2025, there are no known public proof-of-concept exploits or active exploitation campaigns targeting this vulnerability. However, vulnerabilities of this nature in widely used web browsers are prime targets for exploit development by threat actors. Organizations should assume that an exploit will become available in the near future.

Analyst Recommendation

Given the high CVSS score and the potential for remote code execution with minimal user interaction, this vulnerability presents a critical risk to the organization. All vulnerable versions of Mozilla Firefox and Firefox ESR must be patched on an emergency basis. Priority should be given to systems used by employees with privileged access or those who handle sensitive data. Although this CVE is not currently listed on the CISA KEV catalog, its severity makes it a likely candidate for future inclusion, and it should be treated with the highest priority.

Executive Summary:
A high-severity vulnerability has been identified in Mozilla Firefox which could allow a remote attacker to execute arbitrary code on a user's system. An attacker could exploit this by tricking a user into visiting a specially crafted malicious website, potentially leading to a full system compromise, data theft, or malware installation. Immediate patching is required to mitigate this significant risk.

Vulnerability Details

CVE-ID: CVE-2025-10535

Affected Software: Mozilla Firefox

Affected Versions: Firefox versions prior to 143

Vulnerability: This vulnerability is a use-after-free error within the browser's rendering engine. By creating a malicious webpage with specific, malformed content, an attacker can trigger a condition where the browser attempts to access a portion of memory that has already been deallocated. This can corrupt memory in a predictable way, leading to a browser crash and creating an opportunity for the attacker to execute arbitrary code with the privileges of the logged-in user.

Business Impact

This vulnerability is rated as High severity with a CVSS score of 7.5. Successful exploitation could have a significant business impact by allowing an attacker to compromise employee workstations. Potential consequences include the exfiltration of sensitive corporate data, theft of user credentials stored in the browser, installation of persistent malware such as ransomware or spyware, and using the compromised machine as a foothold to launch further attacks against the internal network.

Remediation Plan

Immediate Action: Apply vendor security updates immediately. All instances of Mozilla Firefox on corporate systems must be updated to version 143 or later to patch this vulnerability. IT administrators should use endpoint management systems to enforce and verify the update across the entire organization.

Proactive Monitoring: Monitor for exploitation attempts and review access logs. Security teams should monitor for anomalous outbound network traffic from endpoints, especially from Firefox processes. Endpoint Detection and Response (EDR) systems should be configured to alert on Firefox spawning unexpected child processes (e.g., cmd.exe, powershell.exe) or writing executable files to disk.

Compensating Controls: If immediate patching is not possible, consider implementing temporary compensating controls. Enhance web filtering to block uncategorized or newly registered domains. Ensure EDR and antivirus solutions are up-to-date with the latest signatures and behavioral detection rules to identify and block post-exploitation activity.

Exploitation Status

Public Exploit Available: false

Analyst Notes: As of September 17, 2025, there is no known public proof-of-concept or active exploitation of this vulnerability in the wild. However, vulnerabilities of this type in major web browsers are prime targets for threat actors and are often reverse-engineered to develop exploits. This vulnerability is not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog.

Analyst Recommendation

This vulnerability presents a critical risk to the organization, as it can be exploited through simple web browsing with no user interaction beyond visiting a malicious site. Although there is no evidence of active exploitation, the high severity and potential for remote code execution demand immediate action. It is strongly recommended that all vulnerable versions of Mozilla Firefox are updated to version 143 or newer as the top priority. Organizations must verify patch compliance and maintain heightened monitoring for any indicators of compromise.

Executive Summary:
A high-severity vulnerability has been discovered in Mozilla Firefox and Thunderbird, which could allow a remote attacker to execute arbitrary code on a user's system. An attacker could exploit this by tricking a user into visiting a specially crafted webpage or opening a malicious email, potentially leading to a full system compromise, data theft, or the installation of malware such as ransomware.

Vulnerability Details

CVE-ID: CVE-2025-10534

Affected Software: Mozilla Firefox, Mozilla Thunderbird

Affected Versions: Firefox versions prior to 143 and Thunderbird versions prior to 143.

Vulnerability: This vulnerability is a use-after-free error within the browser's rendering engine. An attacker can create a malicious website or HTML email containing specific JavaScript and DOM manipulation sequences that cause the browser to incorrectly handle memory pointers for certain objects. When the user visits the site or opens the email, the crafted content triggers the memory corruption, which can be leveraged by the attacker to execute arbitrary code with the privileges of the logged-in user.

Business Impact

This vulnerability presents a significant risk to the organization, classified as High severity with a CVSS score of 8.1. Successful exploitation could grant an attacker initial access to the corporate network through a compromised employee workstation. Potential consequences include the exfiltration of sensitive corporate data, theft of user credentials, deployment of ransomware, lateral movement to other critical systems, and reputational damage. The widespread use of Firefox and Thunderbird as primary web and email clients makes this a critical threat that could impact a large number of users within the organization.

Remediation Plan

Immediate Action: The primary remediation is to apply the security updates provided by the vendor. All instances of Mozilla Firefox and Thunderbird must be updated to version 143 or later immediately. Following the updates, system administrators should monitor for any signs of exploitation attempts by reviewing endpoint protection logs and network traffic for anomalous behavior originating from workstations.

Proactive Monitoring: Security teams should configure monitoring tools to detect potential exploitation. Key indicators to look for include:

• Unusual child processes being spawned by firefox.exe or thunderbird.exe.
• Network connections from workstations to unknown or suspicious IP addresses or domains.
• Alerts from Endpoint Detection and Response (EDR) solutions related to memory corruption exploits or suspicious script execution.
• Review of web proxy and DNS logs for visits to newly registered or uncategorized domains.

Compensating Controls: If immediate patching is not feasible, the following controls can help reduce the risk:

• Ensure web filtering and DNS security solutions are in place to block access to known malicious and uncategorized websites.
• Utilize browser isolation technology to render web content in a secure, remote environment, preventing malicious code from reaching the endpoint.
• Enforce strict application control policies to prevent the execution of unauthorized software on workstations.
• Conduct user awareness training to reinforce caution against clicking on suspicious links or opening attachments from unknown sources.

Exploitation Status

Public Exploit Available: false

Analyst Notes: As of September 17, 2025, there are no known public proof-of-concept exploits or reports of this vulnerability being actively exploited in the wild. However, due to the high severity and the large attack surface, it is highly probable that threat actors will reverse-engineer the patch and develop a working exploit in the near future.

Analyst Recommendation

Given the high severity (CVSS 8.1) of this vulnerability and its potential for remote code execution, this issue must be addressed with extreme urgency. Although it is not currently listed on the CISA KEV (Known Exploited Vulnerabilities) catalog, its characteristics make it a prime candidate for future inclusion. We strongly recommend that organizations prioritize the immediate deployment of vendor-supplied patches across all managed endpoints to mitigate the risk of system compromise, data breaches, and further network intrusion. This vulnerability should be considered a critical threat to the organization.

Executive Summary:
A high-severity vulnerability has been discovered in specific versions of Mozilla Firefox and Firefox ESR. Successful exploitation could allow a remote attacker to execute arbitrary code on a user's system simply by convincing them to visit a specially crafted webpage, potentially leading to a full system compromise, data theft, or installation of malware.

Vulnerability Details

CVE-ID: CVE-2025-10533

Affected Software: This Multiple Products

Affected Versions: Firefox versions prior to 143 and Firefox ESR versions prior to 115.

Vulnerability: This vulnerability is a use-after-free condition within the browser's JavaScript engine. An attacker can create a malicious webpage with specially crafted JavaScript code that, when processed by an affected browser, triggers the premature release of a memory object. The attacker can then subsequently access this freed memory to corrupt data structures, leading to a crash and enabling the execution of arbitrary code with the privileges of the logged-in user.

Business Impact

This vulnerability is rated as High severity with a CVSS score of 8.8. A successful exploit could have a significant negative impact on the organization. An attacker could compromise an employee's workstation, leading to the theft of sensitive corporate data, financial information, or user credentials. Furthermore, a compromised system could be used as a pivot point to launch further attacks against the internal network, or it could be infected with malware such as ransomware, causing severe operational disruption and financial loss.

Remediation Plan

Immediate Action: The primary remediation is to apply vendor-supplied security updates immediately. All instances of Mozilla Firefox should be updated to version 143 or later, and all instances of Firefox ESR should be updated to version 115 or later. Following the updates, security teams should actively monitor for any signs of exploitation attempts and review web proxy and endpoint logs for suspicious activity originating from browser processes.

Proactive Monitoring: Implement enhanced monitoring on endpoints and network egress points. Look for unusual outbound connections from workstations to unknown IP addresses or domains. Endpoint Detection and Response (EDR) solutions should be configured to alert on anomalous processes being spawned by firefox.exe, unexpected file modifications, or suspicious script execution.

Compensating Controls: If immediate patching is not feasible, consider implementing compensating controls to reduce the risk. Deploy script-blocking browser extensions to prevent the execution of potentially malicious code, though this may impact the functionality of legitimate websites. Enhance user awareness by communicating the threat and reminding employees not to click on links from untrusted sources. Ensure network firewalls are configured to block outbound traffic to known malicious destinations.

Exploitation Status

Public Exploit Available: false

Analyst Notes: As of September 16, 2025, there are no known public exploits for this vulnerability, and it is not listed on CISA's Known Exploited Vulnerabilities (KEV) catalog. However, given the high severity and the potential for remote code execution, it is highly probable that threat actors are actively working to develop exploit code. Organizations should operate under the assumption that an exploit will become available shortly.

Analyst Recommendation

This vulnerability represents a critical risk to the organization due to its high severity (CVSS 8.8) and the ease of exploitation via web browsing. The immediate patching of all affected Firefox and Firefox ESR installations must be the highest priority. Although this CVE is not yet on the CISA KEV list, its characteristics make it a prime target for widespread exploitation. We recommend treating this as an emergency change and deploying the necessary updates across all corporate endpoints without delay to prevent potential system compromise and subsequent data breaches.

Executive Summary:
A high-severity vulnerability has been identified in Mozilla Firefox and Firefox ESR, which could allow a remote attacker to execute arbitrary code on a user's system. Successful exploitation requires a user to visit a specially crafted, malicious webpage, potentially leading to data theft, malware installation, or further compromise of the corporate network.

Vulnerability Details

CVE-ID: CVE-2025-10527

Affected Software: Mozilla Firefox and Firefox ESR

Affected Versions:

• Firefox versions prior to 143
• Firefox ESR versions prior to 140

Vulnerability:
This vulnerability is a use-after-free condition within the browser's rendering engine. An attacker can exploit this flaw by creating a malicious webpage with specific HTML and JavaScript elements that manipulate memory objects in a way that causes the browser to reference memory that has already been deallocated. When a user with an affected version of Firefox navigates to this page, the flawed memory access can be triggered, corrupting the browser's memory state and allowing the attacker to execute arbitrary code on the victim's machine within the security context of the browser.

Business Impact

This vulnerability is rated as High severity with a CVSS score of 7.1. Exploitation could have a significant business impact by compromising employee workstations. An attacker could leverage this access to steal sensitive corporate data viewed in the browser (such as credentials, financial information, or customer data), install persistent malware like ransomware or spyware, or use the compromised machine as a foothold to move laterally within the organization's internal network. Given the widespread use of Firefox in enterprise environments, a large number of systems may be at risk.

Remediation Plan

Immediate Action:
The primary remediation is to apply vendor-supplied security updates across all affected systems immediately. System administrators should ensure that all installations of Mozilla Firefox are updated to version 143 or later, and all installations of Mozilla Firefox ESR are updated to version 140 or later. Following the updates, monitor endpoint security logs and network traffic for any signs of attempted exploitation.

Proactive Monitoring:

• Network Logs: Monitor web proxy and DNS logs for connections from corporate endpoints to newly registered domains, known malicious URLs, or unusual IP addresses.
• Endpoint Detection and Response (EDR): Configure EDR solutions to alert on suspicious child processes spawned by firefox.exe, unexpected file writes to disk from the browser process, or attempts by the browser to execute system commands.
• Intrusion Detection/Prevention Systems (IDS/IPS): Deploy network security signatures specific to this CVE as they become available to detect and block exploit traffic.

Compensating Controls:
If immediate patching is not feasible, the following controls can help reduce risk:

• User Awareness: Advise all employees to exercise caution when clicking links in emails or visiting unfamiliar websites.
• Web Filtering: Use a secure web gateway to block access to uncategorized or known malicious websites.
• Principle of Least Privilege: Ensure users are not running web browsers with local administrator privileges, which would limit the post-exploitation impact of an attack.

Exploitation Status

Public Exploit Available: false

Analyst Notes:
As of September 16, 2025, there are no known public proof-of-concept exploits or reports of this vulnerability being actively exploited in the wild. However, vulnerabilities in widely-used web browsers are high-value targets for threat actors, and exploit code is often developed and deployed rapidly after a patch is released.

Analyst Recommendation

Given the high severity (CVSS 7.1) of this vulnerability and its potential for remote code execution, we strongly recommend that organizations prioritize the deployment of the provided security updates. Although this vulnerability is not currently listed in the CISA KEV catalog and is not under active exploitation, the risk of compromise is significant. Patching all vulnerable Firefox and Firefox ESR installations should be treated as a high-priority task and completed within the organization's standard remediation timeframe for critical vulnerabilities.