CVE-2021-25946
📋 TL;DR
CVE-2021-25946 is a prototype pollution vulnerability in nconf-toml, a Node.js configuration file parser. It allows attackers to modify object prototypes, potentially leading to denial of service or remote code execution. This affects applications using vulnerable versions of the nconf-toml library.
💻 Affected Systems
- nconf-toml
📦 What is this software?
Nconf Toml by Nconf Toml 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 if proper input validation and sandboxing are implemented, though prototype pollution remains dangerous.
🎯 Exploit Status
Exploitation requires the application to parse a malicious TOML file. Public proof-of-concept code demonstrates prototype pollution.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.0.3 and later
Vendor Advisory: https://github.com/RobLoach/nconf-toml/security/advisories/GHSA-5jq7-2j3q-8j3q
Restart Required: Yes
Instructions:
1. Update nconf-toml to version 0.0.3 or later using npm: npm update nconf-toml. 2. Restart the Node.js application to load the updated library.
🔧 Temporary Workarounds
Input validation and sanitization
allImplement strict validation of TOML file inputs to reject malicious content before parsing.
Use alternative configuration parser
allTemporarily replace nconf-toml with a secure alternative like @iarna/toml until patched.
npm uninstall nconf-toml
npm install @iarna/toml
🧯 If You Can't Patch
- Isolate the application in a restricted network segment to limit potential lateral movement.
- Implement strict file upload controls and scan all TOML files with security tools before processing.
🔍 How to Verify
Check if Vulnerable:
Check package.json or run: npm list nconf-toml | grep nconf-tomlCheck Version:
npm list nconf-tomlVerify Fix Applied:
Verify installed version is 0.0.3 or later: npm list nconf-toml📡 Detection & Monitoring
Log Indicators:
- Unexpected application crashes, abnormal memory usage, or errors in TOML parsing logs
Network Indicators:
- Unusual outbound connections from the Node.js process, especially to unknown IPs
SIEM Query:
source="application.log" AND "nconf-toml" AND ("error" OR "crash" OR "unexpected")🔗 References
- https://github.com/RobLoach/nconf-toml/blob/8ade08cd1cfb9691ab7cc5c3514cc05c5085918f/index.js#L8
- https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25946
- https://github.com/RobLoach/nconf-toml/blob/8ade08cd1cfb9691ab7cc5c3514cc05c5085918f/index.js#L8
- https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25946
