CVE-2025-59841
📋 TL;DR
Flag Forge CTF platform versions 2.2.0 through 2.3.0 have a session invalidation vulnerability where authenticated users can continue accessing protected endpoints and CSRF tokens remain valid after logout. This allows unauthorized access to user profiles and potential unauthorized actions. All users of affected versions are impacted.
💻 Affected Systems
- Flag Forge CTF Platform
📦 What is this software?
Flagforge by Flagforge
⚠️ Risk & Real-World Impact
Worst Case
Attackers could maintain persistent access to user accounts, perform unauthorized actions using valid CSRF tokens, and potentially escalate privileges or access sensitive data.
Likely Case
Users who logged out but whose sessions weren't properly invalidated could have their accounts accessed by others using the same device, or attackers could perform unauthorized actions using stolen CSRF tokens.
If Mitigated
With proper session management controls, the impact is limited to temporary session persistence issues that are resolved upon proper logout implementation.
🎯 Exploit Status
Exploitation requires initial authentication but is straightforward once authenticated. The vulnerability is in session management logic.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.3.1
Vendor Advisory: https://github.com/FlagForgeCTF/flagForge/security/advisories/GHSA-h6pr-4cwv-6cjg
Restart Required: Yes
Instructions:
1. Backup your current installation. 2. Update to version 2.3.1 via git pull or package update. 3. Restart the application server. 4. Verify the fix by testing logout functionality.
🔧 Temporary Workarounds
Manual Session Cleanup
allImplement custom session cleanup on logout by invalidating sessions server-side
# Requires modifying application code to properly invalidate sessions on logout
Session Timeout Reduction
allReduce session timeout to minimize window of vulnerability
# Configure shorter session expiration in application settings
🧯 If You Can't Patch
- Implement network segmentation to isolate the Flag Forge instance
- Monitor for unusual post-logout activity and implement additional authentication checks
🔍 How to Verify
Check if Vulnerable:
Test logout functionality: 1. Log in to Flag Forge. 2. Log out. 3. Try accessing /api/profile endpoint. If accessible, system is vulnerable.Check Version:
Check package.json or application version endpoint for version numberVerify Fix Applied:
After patching, repeat the vulnerability test. Post-logout access to protected endpoints should be denied.📡 Detection & Monitoring
Log Indicators:
- Multiple successful API calls from same session ID after logout event
- Access to protected endpoints without recent login
Network Indicators:
- API requests to protected endpoints without corresponding login requests
- CSRF token usage from expired sessions
SIEM Query:
source="flagforge" AND (event="api_access" AND resource="/api/profile") | stats count by session_id | where count > threshold