CVE-2026-25641
📋 TL;DR
CVE-2026-25641 is a sandbox escape vulnerability in SandboxJS library versions before 0.8.29. Attackers can bypass JavaScript sandbox restrictions by passing malicious objects that coerce to different string values during validation versus property access. This affects any application using vulnerable SandboxJS versions for JavaScript isolation.
💻 Affected Systems
- SandboxJS
📦 What is this software?
Sandboxjs by Nyariv
⚠️ Risk & Real-World Impact
Worst Case
Complete sandbox escape allowing arbitrary code execution with the privileges of the hosting application, potentially leading to full system compromise.
Likely Case
Sandbox escape enabling execution of unauthorized JavaScript code within the application context, potentially accessing sensitive data or performing unauthorized actions.
If Mitigated
Limited impact if sandboxed code runs with minimal privileges and in isolated environments, though sandbox integrity would still be compromised.
🎯 Exploit Status
Exploitation requires understanding of JavaScript object coercion and sandbox implementation details.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.8.29
Vendor Advisory: https://github.com/nyariv/SandboxJS/security/advisories/GHSA-7x3h-rm86-3342
Restart Required: Yes
Instructions:
1. Update SandboxJS dependency to version 0.8.29 or later. 2. Restart any applications using SandboxJS. 3. Verify the update was successful.
🔧 Temporary Workarounds
Disable SandboxJS Usage
allTemporarily disable or remove SandboxJS functionality until patching is possible.
🧯 If You Can't Patch
- Isolate applications using SandboxJS in network segments with restricted access.
- Implement additional input validation and monitoring for suspicious JavaScript execution patterns.
🔍 How to Verify
Check if Vulnerable:
Check package.json or dependency files for SandboxJS version below 0.8.29.Check Version:
npm list sandboxjsVerify Fix Applied:
Confirm SandboxJS version is 0.8.29 or higher in package.json and verify application functionality.📡 Detection & Monitoring
Log Indicators:
- Unusual JavaScript execution patterns
- Sandbox-related error messages
- Unexpected process spawns from JavaScript contexts
Network Indicators:
- Outbound connections from JavaScript sandbox processes to unexpected destinations
SIEM Query:
process.name:node AND cmdline:*sandbox* AND (event.action:process_start OR event.action:network_connection)🔗 References
- https://github.com/nyariv/SandboxJS/blob/6103d7147c4666fe48cfda58a4d5f37005b43754/src/executor.ts#L304-L304
- https://github.com/nyariv/SandboxJS/commit/67cb186c41c78c51464f70405504e8ef0a6e43c3
- https://github.com/nyariv/SandboxJS/security/advisories/GHSA-7x3h-rm86-3342
- https://github.com/nyariv/SandboxJS/security/advisories/GHSA-7x3h-rm86-3342
