CVE-2026-25222
📋 TL;DR
This timing attack vulnerability in PolarLearn allows unauthenticated attackers to enumerate valid user email addresses by measuring login response times. Attackers can determine which email addresses are registered on the platform, enabling targeted phishing or credential stuffing attacks. All PolarLearn instances running vulnerable versions are affected.
💻 Affected Systems
- PolarLearn
⚠️ Risk & Real-World Impact
Worst Case
Attackers build complete user directory, enabling targeted credential stuffing, phishing campaigns, or social engineering attacks against all registered users.
Likely Case
Attackers enumerate some valid email addresses for targeted phishing or credential stuffing against vulnerable accounts.
If Mitigated
Limited to unsuccessful login attempts logging, with no user enumeration possible.
🎯 Exploit Status
Simple timing attack requiring only network access and ability to measure response times.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in commit 6c276855172c7310cce0df996cb47ffe0d886741
Vendor Advisory: https://github.com/polarnl/PolarLearn/security/advisories/GHSA-wcr9-mvr9-4qh5
Restart Required: Yes
Instructions:
1. Update to latest PolarLearn version. 2. Apply commit 6c276855172c7310cce0df996cb47ffe0d886741. 3. Restart PolarLearn service.
🔧 Temporary Workarounds
Rate Limiting
allImplement strict rate limiting on login endpoints to slow enumeration attempts
WAF Rules
allConfigure WAF to detect and block rapid login attempts from single IPs
🧯 If You Can't Patch
- Implement network-level rate limiting on login endpoints
- Monitor for unusual login attempt patterns and block suspicious IPs
🔍 How to Verify
Check if Vulnerable:
Measure login response times for valid vs invalid emails - vulnerable if significant time difference existsCheck Version:
Check PolarLearn version in admin interface or configuration filesVerify Fix Applied:
Test login response times - fixed if response times are consistent regardless of email validity📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts for different email addresses from same IP
- Unusual pattern of login attempts
Network Indicators:
- Rapid sequential POST requests to login endpoint
- Consistent timing patterns in login requests
SIEM Query:
source="PolarLearn" action="login_failed" | stats count by src_ip | where count > threshold