CVE-2021-45470
📋 TL;DR
CVE-2021-45470 is a regular expression injection vulnerability in cve-search's DatabaseLayer.py that allows attackers to inject malicious regex patterns. This can lead to ReDoS (regular expression denial of service) attacks causing service degradation or potentially other impacts through regex manipulation. Organizations using cve-search versions before 4.1.0 for vulnerability management are affected.
💻 Affected Systems
- cve-search
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete service denial through ReDoS causing CPU exhaustion, potentially allowing regex injection to bypass security controls or manipulate database queries.
Likely Case
Service degradation through ReDoS attacks causing performance issues and potential denial of service for legitimate users.
If Mitigated
Minimal impact with proper input validation and rate limiting in place, though regex injection vectors remain.
🎯 Exploit Status
Exploitation requires ability to submit input to affected regex operations; no authentication bypass needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.1.0
Vendor Advisory: https://github.com/cve-search/cve-search/commit/c621f9f0693a728b93ff3b964f948a1d25917207
Restart Required: Yes
Instructions:
1. Backup current cve-search installation. 2. Update to version 4.1.0 or later using git: 'git pull origin master' or download release. 3. Restart cve-search services. 4. Verify update with version check.
🔧 Temporary Workarounds
Input Validation Filter
allImplement input validation to reject or sanitize regex patterns in user input
# Add input validation in DatabaseLayer.py before regex operations
# Example: validate regex patterns are safe before processing
Rate Limiting
linuxImplement rate limiting on API endpoints to mitigate ReDoS impact
# Configure web server or application rate limiting
# Example: nginx: limit_req_zone $binary_remote_addr zone=api:10m rate=10r/s
🧯 If You Can't Patch
- Implement strict input validation to reject complex regex patterns from untrusted sources
- Deploy WAF rules to detect and block malicious regex patterns in requests
🔍 How to Verify
Check if Vulnerable:
Check cve-search version: if version < 4.1.0, system is vulnerable. Review DatabaseLayer.py for regex injection patterns.Check Version:
python -c "import cve_search; print(cve_search.__version__)" or check git tag/release filesVerify Fix Applied:
Verify version is 4.1.0 or later and examine DatabaseLayer.py for proper input sanitization in regex operations.📡 Detection & Monitoring
Log Indicators:
- Unusually long regex patterns in requests
- High CPU usage on cve-search processes
- Multiple failed regex operations
Network Indicators:
- Repeated requests with complex regex patterns
- Unusual request patterns to DatabaseLayer endpoints
SIEM Query:
source="cve-search" AND ("regex" OR "DatabaseLayer") AND (status=500 OR duration>5s)🔗 References
- https://github.com/cve-search/cve-search/commit/c621f9f0693a728b93ff3b964f948a1d25917207
- https://github.com/cve-search/cve-search/compare/v4.0...v4.1.0
- https://github.com/cve-search/cve-search/pull/629
- https://github.com/cve-search/cve-search/commit/c621f9f0693a728b93ff3b964f948a1d25917207
- https://github.com/cve-search/cve-search/compare/v4.0...v4.1.0
- https://github.com/cve-search/cve-search/pull/629
