CVE-2026-25142
📋 TL;DR
CVE-2026-25142 is a critical sandbox escape vulnerability in SandboxJS library versions before 0.8.27. Attackers can use the __lookupGetter__ method to access prototypes and execute arbitrary code outside the sandbox, potentially leading to remote code execution. Any application using vulnerable SandboxJS versions for JavaScript isolation is affected.
💻 Affected Systems
- SandboxJS
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise via remote code execution, allowing attackers to execute arbitrary commands with application privileges.
Likely Case
Sandbox escape leading to unauthorized access to host system resources, data exfiltration, or lateral movement.
If Mitigated
Limited impact if sandboxed code has minimal privileges and proper network segmentation exists.
🎯 Exploit Status
Proof-of-concept available in GitHub advisory. Exploitation requires ability to execute JavaScript within the sandbox.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.8.27
Vendor Advisory: https://github.com/nyariv/SandboxJS/security/advisories/GHSA-9p4w-fq8m-2hp7
Restart Required: Yes
Instructions:
1. Update SandboxJS dependency to version 0.8.27 or later. 2. Update package.json to specify 'sandboxjs': '>=0.8.27'. 3. Run npm update or yarn upgrade. 4. Restart the application.
🔧 Temporary Workarounds
Disable __lookupGetter__ in sandbox
allOverride or block __lookupGetter__ method in sandbox configuration
// In sandbox configuration: { blacklist: ['__lookupGetter__'] }
🧯 If You Can't Patch
- Isolate sandboxed code in container with minimal privileges
- Implement strict input validation and limit sandbox execution to trusted code only
🔍 How to Verify
Check if Vulnerable:
Check package.json or node_modules/sandboxjs/package.json for version <0.8.27Check Version:
npm list sandboxjs | grep sandboxjsVerify Fix Applied:
Verify installed version is 0.8.27 or higher using npm list sandboxjs📡 Detection & Monitoring
Log Indicators:
- Unusual JavaScript execution patterns
- Sandbox escape attempts in application logs
Network Indicators:
- Unexpected outbound connections from sandboxed processes
SIEM Query:
process.name:node AND cmdline:*sandbox* AND (event.action:execute OR event.action:spawn)