CVE-2021-41167
📋 TL;DR
CVE-2021-41167 is a concurrency control vulnerability in the modern-async JavaScript library where forEachSeries and forEachLimit functions fail to limit concurrent operations as intended. This affects any application using these functions expecting controlled concurrency, potentially leading to resource exhaustion or unexpected behavior. The vulnerability impacts all projects using affected versions of modern-async.
💻 Affected Systems
- modern-async
📦 What is this software?
Modern Async by Modern Async Project
⚠️ Risk & Real-World Impact
Worst Case
Resource exhaustion leading to denial of service, application crashes, or unexpected parallel execution of sensitive operations that should be serialized.
Likely Case
Performance degradation, unexpected application behavior, or race conditions in dependent code that relies on controlled concurrency.
If Mitigated
Minimal impact if the vulnerable functions aren't used for critical operations or if the application has robust error handling and resource limits.
🎯 Exploit Status
Exploitation requires understanding of the specific application's use of the vulnerable functions. No known public exploits exist.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.0.4
Vendor Advisory: https://github.com/nicolas-van/modern-async/security/advisories/GHSA-3pcq-34w5-p4g2
Restart Required: Yes
Instructions:
1. Update package.json to specify modern-async version 1.0.4 or higher. 2. Run 'npm update modern-async' or 'yarn upgrade modern-async'. 3. Restart the application to load the updated library.
🔧 Temporary Workarounds
No workaround available
allThe advisory states there is no workaround. The only solution is to upgrade to the patched version.
🧯 If You Can't Patch
- Review and refactor code to avoid using forEachSeries and forEachLimit functions from modern-async
- Implement application-level concurrency controls and resource limits to mitigate potential DoS scenarios
🔍 How to Verify
Check if Vulnerable:
Check package.json or package-lock.json for modern-async version. If version is below 1.0.4, the system is vulnerable if using forEachSeries or forEachLimit.Check Version:
npm list modern-async | grep modern-async OR check package.json for versionVerify Fix Applied:
Verify modern-async version is 1.0.4 or higher in package.json and that the application restarted successfully.📡 Detection & Monitoring
Log Indicators:
- Unusual resource consumption patterns
- Application errors related to concurrency or async operations
Network Indicators:
- Increased resource usage without corresponding traffic increase
SIEM Query:
Search for application logs containing 'modern-async' version strings below 1.0.4🔗 References
- https://github.com/nicolas-van/modern-async/commit/0010d28de1b15d51db3976080e26357fa7144436
- https://github.com/nicolas-van/modern-async/issues/5
- https://github.com/nicolas-van/modern-async/security/advisories/GHSA-3pcq-34w5-p4g2
- https://github.com/nicolas-van/modern-async/commit/0010d28de1b15d51db3976080e26357fa7144436
- https://github.com/nicolas-van/modern-async/issues/5
- https://github.com/nicolas-van/modern-async/security/advisories/GHSA-3pcq-34w5-p4g2
