CVE-2025-50537
📋 TL;DR
A stack overflow vulnerability in ESLint versions before 9.26.0 allows denial of service when processing test cases with circular references. This affects developers and CI/CD pipelines using ESLint's RuleTester for custom rule validation. The vulnerability is triggered during test case serialization checks.
💻 Affected Systems
- ESLint
⚠️ Risk & Real-World Impact
Worst Case
Complete denial of service causing ESLint processes to crash, potentially disrupting CI/CD pipelines and development workflows.
Likely Case
Local development environment crashes when running specific test suites with circular references in RuleTester.
If Mitigated
Minimal impact if proper input validation prevents circular references from reaching vulnerable code paths.
🎯 Exploit Status
Exploit requires developer access to modify test cases. Public proof-of-concept demonstrates the crash condition.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 9.26.0
Vendor Advisory: https://github.com/eslint/eslint/issues/19646
Restart Required: No
Instructions:
1. Update ESLint package: npm update eslint
2. Verify version: eslint --version
3. Ensure version is 9.26.0 or higher
🔧 Temporary Workarounds
Avoid circular references in RuleTester
allModify test cases to avoid passing objects with circular references to RuleTester.run() method
🧯 If You Can't Patch
- Implement input validation to detect and reject circular reference objects before passing to RuleTester
- Monitor ESLint processes for crashes and implement automatic restart mechanisms
🔍 How to Verify
Check if Vulnerable:
Check ESLint version: eslint --version. If version is below 9.26.0, system is vulnerable.Check Version:
eslint --versionVerify Fix Applied:
After update, verify version is 9.26.0 or higher and test that RuleTester no longer crashes with circular references.📡 Detection & Monitoring
Log Indicators:
- ESLint process crashes with stack overflow errors
- RuleTester test failures with recursion depth exceeded
SIEM Query:
process.name:"eslint" AND (error:"stack overflow" OR error:"maximum call stack size exceeded")