Heap-based buffer overflow in Microsoft Defender allows an unauthorized attacker to execute code over a network
Description
Heap-based buffer overflow in Microsoft Defender allows an unauthorized attacker to execute code over a network
AI Analyst Comment
Remediation
Apply vendor security updates immediately. Monitor for exploitation attempts and review access logs.
---METADATA---
VENDOR: Microsoft
PRODUCT: Defender (Malware Protection Engine)
AFFECTED_VERSIONS: 1.1.0.0 up to (excluding) 1.1.26040.8
CONFIDENCE: high
MISSING: none
---END_METADATA---
Description Summary:
A heap-based buffer overflow in the Microsoft Malware Protection Engine allows an unauthorized attacker to execute arbitrary code over a network.
Executive Summary:
A heap-based buffer overflow in the Microsoft Malware Protection Engine could allow an unauthorized attacker to achieve remote code execution.
Vulnerability Details
CVE-ID: CVE-2026-45584
Affected Software: Microsoft Defender (Malware Protection Engine)
Affected Versions: 1.1.0.0 up to (excluding) 1.1.26040.8
Vulnerability: This is a heap-based buffer overflow (CWE-122) in the Malware Protection Engine. An unauthorized attacker can trigger this vulnerability over a network, potentially leading to arbitrary code execution.
Business Impact
With a CVSS score of 8.1, this vulnerability poses a critical risk as it allows for remote code execution, which could result in full system takeover. The potential for unauthorized access to sensitive data and disruption of services makes this a high-priority remediation item.
Remediation Plan
Immediate Action: Ensure that the Microsoft Malware Protection Engine is updated to version 1.1.26040.8 or later immediately.
Proactive Monitoring: Monitor network traffic and endpoint telemetry for unusual process execution or attempts to exploit memory vulnerabilities.
Compensating Controls: Ensure standard endpoint protection policies are active and that the system is configured to receive automatic signature and engine updates from Microsoft.
Exploitation Status
Public Exploit Available: false
Analyst Notes: As of May 21, 2026, there is no public information indicating active exploitation of this vulnerability. However, due to the nature of the flaw, the potential for exploitation is high.
Analyst Recommendation
Remote code execution vulnerabilities in security products are extremely dangerous because they can be exploited before a user even interacts with a malicious file. Organizations must verify that their Microsoft Defender engines have been automatically updated to the patched version to mitigate this risk.