SandboxJS is a JavaScript sandboxing library. Prior to 0.8.27, SanboxJS does not properly restrict __lookupGetter__ which can be used to obtain protot...
Description
SandboxJS is a JavaScript sandboxing library. Prior to 0.8.27, SanboxJS does not properly restrict __lookupGetter__ which can be used to obtain prototypes, which can be used for escaping the sandbox / remote code execution. This vulnerability is fixed in 0.8.27.
AI Analyst Comment
Remediation
Update SandboxJS is a JavaScript sandboxing Multiple Products to the latest version. Monitor for exploitation attempts and review access logs.
Executive Summary:
A critical vulnerability has been identified in the SandboxJS library, a tool designed to safely execute untrusted JavaScript code. This flaw allows an attacker to bypass the library's security restrictions and execute arbitrary code on the underlying server. Successful exploitation could lead to a complete system compromise, resulting in data theft, service disruption, or further network intrusion.
Vulnerability Details
CVE-ID: CVE-2026-25142
Affected Software: SandboxJS library
Affected Versions: Versions prior to 0.8.27
Vulnerability: The SandboxJS library fails to properly restrict access to the
__lookupGetter__JavaScript object method. An attacker can craft malicious JavaScript code that leverages this method to access and modify object prototypes. By manipulating the prototype chain, the attacker can gain access to powerful, unrestricted functions outside of the sandbox environment, such as theFunctionconstructor, ultimately leading to a sandbox escape and remote code execution (RCE) on the host system.Business Impact
This vulnerability is rated as critical severity with a CVSS score of 10. A successful exploit would grant an attacker the ability to execute commands on the server with the same privileges as the application running the SandboxJS library. This could lead to a complete loss of confidentiality, integrity, and availability of the affected system and its data. Potential consequences include theft of sensitive data, deployment of ransomware, manipulation of application data, or using the compromised server as a pivot point to attack other systems within the organization's network.
Remediation Plan
Immediate Action: All systems utilizing the SandboxJS library must be immediately updated to version 0.8.27 or later, which contains the fix for this vulnerability. After patching, review application and system logs for any signs of exploitation that may have occurred prior to the update.
Proactive Monitoring: Implement enhanced monitoring on affected systems. Security teams should look for suspicious patterns in logs, such as unexpected process creation by the application, unusual network connections, or logs of user-submitted JavaScript containing strings like
__lookupGetter__,prototype, orconstructor.Compensating Controls: If immediate patching is not feasible, consider implementing the following compensating controls:
Exploitation Status
Public Exploit Available: false
Analyst Notes: As of February 2, 2026, there are no known public exploits targeting this vulnerability. However, given the critical CVSS score of 10 and the public disclosure of the vulnerability's technical details, it is highly probable that proof-of-concept exploits will be developed and released by security researchers or malicious actors in the near future.
Analyst Recommendation
Due to the critical severity (CVSS 10) of this vulnerability and the high risk of complete system compromise, immediate remediation is strongly recommended. Organizations must prioritize applying the update to version 0.8.27 or later across all affected applications without delay. Although this CVE is not currently on the CISA KEV list, its characteristics make it a prime candidate for widespread exploitation, and it should be treated with the highest urgency.