CVE-2023-30581
📋 TL;DR
This vulnerability allows attackers to bypass Node.js's experimental policy mechanism by using __proto__ to require modules outside the policy.json definition. It affects all users using the experimental policy feature in Node.js v16, v18, and v20. The policy mechanism is designed to restrict module loading but this bypass defeats those restrictions.
💻 Affected Systems
- Node.js
📦 What is this software?
Node.js by Nodejs
Node.js by Nodejs
Node.js by Nodejs
⚠️ Risk & Real-World Impact
Worst Case
Attackers could load arbitrary malicious modules, potentially leading to remote code execution, data exfiltration, or complete system compromise.
Likely Case
Unauthorized module loading that violates security policies, potentially enabling privilege escalation or access to restricted functionality.
If Mitigated
Limited impact if policy mechanism isn't used or if proper input validation and sandboxing are in place.
🎯 Exploit Status
Exploitation requires the policy mechanism to be enabled and attacker to be able to inject/modify JavaScript code.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Node.js v16.20.1, v18.16.1, v20.3.1
Vendor Advisory: https://nodejs.org/en/blog/vulnerability/june-2023-security-releases
Restart Required: Yes
Instructions:
1. Check current Node.js version: node --version
2. Update to patched version using package manager:
- npm: npm install -g node@latest
- nvm: nvm install 20.3.1 && nvm use 20.3.1
- System package manager (apt/yum/etc.)
3. Restart all Node.js applications and services.
🔧 Temporary Workarounds
Disable Policy Mechanism
allRemove --experimental-policy flag from Node.js startup if not required
Remove any --experimental-policy flags from startup scripts, package.json scripts, and service configurations
Restrict Module Access
allImplement additional layer of module access controls outside policy mechanism
Implement file system permissions, containerization, or additional validation layers
🧯 If You Can't Patch
- Disable the experimental policy mechanism entirely if not required
- Implement strict input validation and sandboxing for all user-provided JavaScript
🔍 How to Verify
Check if Vulnerable:
Check if Node.js version is below v16.20.1, v18.16.1, or v20.3.1 AND policy mechanism is enabled with --experimental-policy flagCheck Version:
node --versionVerify Fix Applied:
Verify Node.js version is at least v16.20.1, v18.16.1, or v20.3.1 using node --version📡 Detection & Monitoring
Log Indicators:
- Unexpected module loading attempts
- Policy violation warnings
- Errors related to __proto__ manipulation
Network Indicators:
- Unusual outbound connections from Node.js processes
- Unexpected module downloads
SIEM Query:
process.name:"node" AND (cmdline:"--experimental-policy" OR event.action:"module_load")