CVE-2026-25881
📋 TL;DR
This CVE describes a sandbox escape vulnerability in SandboxJS library versions before 0.8.31. It allows sandboxed JavaScript code to bypass isolation protections and modify host-side built-in prototypes, potentially leading to prototype pollution attacks. Applications using vulnerable SandboxJS versions for JavaScript sandboxing are affected.
💻 Affected Systems
- SandboxJS
📦 What is this software?
Sandboxjs by Nyariv
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution (RCE) on the host system through prototype pollution leading to command execution via sensitive sinks like execSync.
Likely Case
Prototype pollution enabling privilege escalation, data manipulation, or denial of service within the application context.
If Mitigated
Limited impact if sandboxed code has minimal privileges and no sensitive sinks are exposed.
🎯 Exploit Status
Proof of concept exists in the security advisory. Exploitation requires the ability to execute JavaScript within the sandbox.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.8.31
Vendor Advisory: https://github.com/nyariv/SandboxJS/security/advisories/GHSA-ww7g-4gwx-m7wj
Restart Required: Yes
Instructions:
1. Update SandboxJS dependency to version 0.8.31 or later. 2. Update package.json to specify 'sandboxjs': '>=0.8.31'. 3. Run npm update or yarn update. 4. Restart the application.
🔧 Temporary Workarounds
Disable sandboxed JavaScript execution
allTemporarily disable or remove SandboxJS functionality until patching is possible.
Comment out or remove SandboxJS initialization and usage in application code
Implement input validation
allAdd strict validation and sanitization of all JavaScript code before passing to SandboxJS.
Implement whitelist validation for allowed JavaScript operations
🧯 If You Can't Patch
- Isolate the application in a container or VM with minimal privileges
- Implement network segmentation to limit potential lateral movement
🔍 How to Verify
Check if Vulnerable:
Check package.json or node_modules for SandboxJS version below 0.8.31Check Version:
npm list sandboxjs | grep sandboxjsVerify Fix Applied:
Verify SandboxJS version is 0.8.31 or higher in package.json and node_modules📡 Detection & Monitoring
Log Indicators:
- Unusual JavaScript execution patterns
- Prototype modification attempts in sandbox context
Network Indicators:
- Unexpected outbound connections from application after sandbox execution
SIEM Query:
source="application_logs" AND ("sandboxjs" OR "prototype") AND ("error" OR "unusual")