CVE-2020-7707
📋 TL;DR
CVE-2020-7707 is a prototype pollution vulnerability in property-expr package versions before 2.0.3. Attackers can inject malicious properties into JavaScript objects, potentially leading to remote code execution or denial of service. This affects any application using vulnerable versions of the property-expr library.
💻 Affected Systems
- property-expr
- applications using property-expr library
📦 What is this software?
Property Expr by Property Expr 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, privilege escalation, or data manipulation through object pollution.
If Mitigated
Limited impact if input validation and sanitization prevent malicious payloads from reaching vulnerable functions.
🎯 Exploit Status
Exploitation requires the application to process attacker-controlled input through the vulnerable setter function.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.0.3 and later
Vendor Advisory: https://github.com/jquense/expr/commit/df846910915d59f711ce63c1f817815bceab5ff7
Restart Required: Yes
Instructions:
1. Update property-expr to version 2.0.3 or later using npm update property-expr. 2. Restart all affected applications. 3. Verify no dependencies are pulling in older versions.
🔧 Temporary Workarounds
Input validation and sanitization
allImplement strict input validation to prevent malicious payloads from reaching the setter function.
🧯 If You Can't Patch
- Implement WAF rules to block prototype pollution payloads in HTTP requests.
- Isolate affected applications in network segments with strict access controls.
🔍 How to Verify
Check if Vulnerable:
Check package.json or run npm list property-expr to see if version is below 2.0.3.Check Version:
npm list property-expr | grep property-exprVerify Fix Applied:
Confirm property-expr version is 2.0.3 or higher using npm list property-expr.📡 Detection & Monitoring
Log Indicators:
- Unusual object property modifications
- Unexpected prototype chain alterations
- Application crashes related to object manipulation
Network Indicators:
- HTTP requests containing __proto__ or constructor payloads
- Unusual patterns in API calls to object manipulation endpoints
SIEM Query:
search 'property-expr' OR 'prototype pollution' in application logs🔗 References
- https://github.com/jquense/expr/commit/df846910915d59f711ce63c1f817815bceab5ff7
- https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-598857
- https://snyk.io/vuln/SNYK-JS-PROPERTYEXPR-598800
- https://github.com/jquense/expr/commit/df846910915d59f711ce63c1f817815bceab5ff7
- https://snyk.io/vuln/SNYK-JAVA-ORGWEBJARSNPM-598857
- https://snyk.io/vuln/SNYK-JS-PROPERTYEXPR-598800
