CVE-2026-25520
📋 TL;DR
SandboxJS versions before 0.8.29 have a critical sandbox escape vulnerability that allows attackers to obtain the host's Function constructor and execute arbitrary code outside the sandbox. This affects any application using vulnerable SandboxJS versions for JavaScript sandboxing. Attackers can potentially execute arbitrary code with the privileges of the hosting application.
💻 Affected Systems
- SandboxJS
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the hosting application with arbitrary code execution, potentially leading to data theft, system takeover, or lateral movement within the network.
Likely Case
Remote code execution on systems running vulnerable SandboxJS, allowing attackers to execute arbitrary commands with application privileges.
If Mitigated
Limited impact if proper network segmentation and least privilege principles are implemented, though sandbox escape still represents a significant security failure.
🎯 Exploit Status
The vulnerability is well-documented with public proof-of-concept available in the advisory. Exploitation requires only the ability to execute JavaScript within the sandbox.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.8.29
Vendor Advisory: https://github.com/nyariv/SandboxJS/security/advisories/GHSA-58jh-xv4v-pcx4
Restart Required: Yes
Instructions:
1. Update SandboxJS to version 0.8.29 or later using npm update sandboxjs
2. Restart any applications using SandboxJS
3. Verify the update was successful by checking the package version
🔧 Temporary Workarounds
Disable SandboxJS Usage
allTemporarily disable or remove SandboxJS functionality until patching is possible
npm uninstall sandboxjs
🧯 If You Can't Patch
- Implement strict input validation and sanitization for all data passed to SandboxJS
- Isolate applications using SandboxJS in network segments with limited access
🔍 How to Verify
Check if Vulnerable:
Check package.json or run 'npm list sandboxjs' to see if version is below 0.8.29Check Version:
npm list sandboxjs | grep sandboxjsVerify Fix Applied:
Verify SandboxJS version is 0.8.29 or higher using 'npm list sandboxjs'📡 Detection & Monitoring
Log Indicators:
- Unusual JavaScript execution patterns
- Sandbox escape attempts in application logs
- Unexpected process spawns from Node.js applications
Network Indicators:
- Outbound connections from Node.js processes to unexpected destinations
- Command and control traffic from application servers
SIEM Query:
process.name:node.exe AND (process.cmd_line:*sandbox* OR process.cmd_line:*SandboxJS*)