CVE-2020-7719
📋 TL;DR
CVE-2020-7719 is a prototype pollution vulnerability in the locutus JavaScript package's php.strings.parse_str function. This allows attackers to inject properties into JavaScript objects, potentially leading to remote code execution or denial of service. Any application using vulnerable versions of locutus is affected.
💻 Affected Systems
- locutus
📦 What is this software?
Locutus by Locutus
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or ransomware deployment.
Likely Case
Denial of service, privilege escalation, or data manipulation through object property injection.
If Mitigated
Limited impact with proper input validation and sandboxing, potentially only causing application crashes.
🎯 Exploit Status
Exploitation requires user input to reach the vulnerable function, but no authentication is needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.0.12
Vendor Advisory: https://github.com/kvz/locutus/pull/418/
Restart Required: No
Instructions:
1. Update package.json to require locutus version 2.0.12 or higher. 2. Run 'npm update locutus' or 'yarn upgrade locutus'. 3. Test application functionality.
🔧 Temporary Workarounds
Input validation and sanitization
allImplement strict input validation for all user inputs passed to parse_str function
Function replacement
allReplace vulnerable parse_str function with a safe alternative
🧯 If You Can't Patch
- Implement strict Content Security Policy (CSP) to limit script execution
- Use web application firewall (WAF) rules to block suspicious input patterns
🔍 How to Verify
Check if Vulnerable:
Check package.json or package-lock.json for locutus version below 2.0.12Check Version:
npm list locutus | grep locutusVerify Fix Applied:
Verify locutus version is 2.0.12 or higher in package.json and node_modules📡 Detection & Monitoring
Log Indicators:
- Unusual parse_str function calls with complex nested objects
- Application crashes or unexpected behavior after user input
Network Indicators:
- HTTP requests containing specially crafted query strings or POST data
SIEM Query:
source="web_server" AND (uri_query CONTAINS "__proto__" OR body CONTAINS "__proto__")