CVE-2021-25941
📋 TL;DR
CVE-2021-25941 is a prototype pollution vulnerability in the 'deep-override' npm package versions 1.0.0 through 1.0.1. This allows attackers to modify JavaScript object prototypes, potentially leading to denial of service or remote code execution. Any application using vulnerable versions of this package is affected.
💻 Affected Systems
- deep-override npm package
📦 What is this software?
Deep Override by Deep Override Project
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or ransomware deployment.
Likely Case
Denial of service through application crashes or instability, with potential for limited code execution in specific configurations.
If Mitigated
Limited impact with proper input validation and sandboxing, though prototype pollution remains dangerous.
🎯 Exploit Status
Prototype pollution exploits are well-documented and relatively easy to weaponize.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.0.2 and later
Vendor Advisory: https://github.com/ASaiAnudeep/deep-override/commit/2aced17651fb684959a6e04b1465a8329b3d5268
Restart Required: Yes
Instructions:
1. Update package.json to specify 'deep-override': '^1.0.2'. 2. Run 'npm update deep-override'. 3. Restart your Node.js application.
🔧 Temporary Workarounds
Input validation and sanitization
allImplement strict input validation for objects passed to deep-override functions.
Object.freeze() on prototypes
allFreeze Object.prototype and other base prototypes to prevent pollution.
Object.freeze(Object.prototype);
Object.freeze(Object);
🧯 If You Can't Patch
- Remove deep-override dependency entirely and replace with alternative object merging libraries.
- Implement network segmentation and strict firewall rules to limit attack surface.
🔍 How to Verify
Check if Vulnerable:
Check package.json or run 'npm list deep-override' to see installed version.Check Version:
npm list deep-overrideVerify Fix Applied:
Verify version is 1.0.2 or higher with 'npm list deep-override' and test object merging with malicious payloads.📡 Detection & Monitoring
Log Indicators:
- Unexpected application crashes
- Unusual object property modifications in logs
- Error messages related to prototype modifications
Network Indicators:
- Unusual HTTP requests with nested object payloads
- Requests containing __proto__ or constructor properties
SIEM Query:
source="application.logs" AND ("__proto__" OR "constructor" OR "prototype pollution")🔗 References
- https://github.com/ASaiAnudeep/deep-override/commit/2aced17651fb684959a6e04b1465a8329b3d5268
- https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25941
- https://github.com/ASaiAnudeep/deep-override/commit/2aced17651fb684959a6e04b1465a8329b3d5268
- https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25941
