CVE-2021-23452
📋 TL;DR
CVE-2021-23452 is a prototype pollution vulnerability in the x-assign JavaScript package that allows attackers to modify the global Object.prototype. This affects all applications using any version of x-assign, potentially leading to denial of service, remote code execution, or privilege escalation.
💻 Affected Systems
- x-assign
📦 What is this software?
X Assign by Binaryops
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data exfiltration, or lateral movement within the network.
Likely Case
Denial of service, application crashes, or unauthorized modification of application behavior leading to data integrity issues.
If Mitigated
Limited impact with proper input validation and security controls, potentially causing application instability but not full compromise.
🎯 Exploit Status
Proof-of-concept code is publicly available. Exploitation requires the attacker to control input passed to x-assign functions.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: No fixed version available - package deprecated
Vendor Advisory: https://snyk.io/vuln/SNYK-JS-XASSIGN-1759314
Restart Required: Yes
Instructions:
1. Remove x-assign from package.json. 2. Run npm uninstall x-assign. 3. Replace x-assign usage with Object.assign() or safer alternatives. 4. Restart all affected applications.
🔧 Temporary Workarounds
Input validation and sanitization
allImplement strict input validation to prevent prototype pollution payloads from reaching x-assign functions
Use Object.freeze() on Object.prototype
allPrevent modification of Object.prototype to block prototype pollution attacks
Object.freeze(Object.prototype);
🧯 If You Can't Patch
- Implement Web Application Firewall (WAF) rules to block prototype pollution patterns
- Isolate affected applications in network segments with strict egress filtering
🔍 How to Verify
Check if Vulnerable:
Check package.json or package-lock.json for x-assign dependency. Run: npm list x-assignCheck Version:
npm list x-assignVerify Fix Applied:
Verify x-assign is no longer in package.json and npm list shows no x-assign installation📡 Detection & Monitoring
Log Indicators:
- Unusual application crashes
- Unexpected prototype modifications in debug logs
- Suspicious object property assignments
Network Indicators:
- Unusual outbound connections from Node.js processes
- Requests containing __proto__ or constructor payloads
SIEM Query:
process.name:"node" AND (event.action:"crash" OR log.message:"*__proto__*" OR log.message:"*prototype*")