CVE-2025-43863
📋 TL;DR
This vulnerability in vantage6 allows attackers with authenticated access to brute-force user passwords through unlimited attempts at the change password endpoint. It affects all vantage6 deployments using vulnerable versions, enabling credential compromise even with strong initial passwords.
💻 Affected Systems
- vantage6
📦 What is this software?
Vantage6 by Vantage6
⚠️ Risk & Real-World Impact
Worst Case
Complete account takeover leading to unauthorized access to federated learning/multi-party computation systems, potential data exfiltration, and privilege escalation within the platform.
Likely Case
Targeted password cracking against specific user accounts, leading to unauthorized access to sensitive federated data and system manipulation.
If Mitigated
Limited impact with proper authentication monitoring and rate limiting in place, though still presents authentication bypass risk.
🎯 Exploit Status
Exploitation requires authenticated access but is trivial to execute using automated tools against the change password endpoint.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.11
Vendor Advisory: https://github.com/vantage6/vantage6/security/advisories/GHSA-j6g5-p62x-58hw
Restart Required: Yes
Instructions:
1. Backup your vantage6 deployment. 2. Update to version 4.11 or later using: pip install vantage6>=4.11. 3. Restart all vantage6 services. 4. Verify the update completed successfully.
🔧 Temporary Workarounds
Rate Limit Change Password Endpoint
allImplement rate limiting on the password change API endpoint to prevent brute-force attempts
# Configure rate limiting in your web server or application firewall
# Example nginx: limit_req_zone $binary_remote_addr zone=changepass:10m rate=1r/m;
# Apply to password change endpoint
Web Application Firewall Rules
allDeploy WAF rules to detect and block excessive password change attempts
# Configure WAF to alert/block on >5 password change attempts per minute per user
# Example ModSecurity rule: SecRule ARGS:password "@gt 5" "id:1001,phase:2,deny"
🧯 If You Can't Patch
- Implement strict monitoring and alerting for multiple failed password change attempts per user
- Enforce strong password policies and consider requiring multi-factor authentication for all users
🔍 How to Verify
Check if Vulnerable:
Check if vantage6 version is below 4.11: python -c "import vantage6; print(vantage6.__version__)"Check Version:
python -c "import vantage6; print('vantage6 version:', vantage6.__version__)"Verify Fix Applied:
Confirm version is 4.11 or higher and test that password change endpoint now has rate limiting or proper validation📡 Detection & Monitoring
Log Indicators:
- Multiple failed password change attempts for same user account
- Rapid sequential POST requests to /api/user/password endpoint
- Unusual authentication patterns following password changes
Network Indicators:
- High volume of requests to password change API endpoint
- Pattern of failed password change attempts from single source
SIEM Query:
source="vantage6" AND (url_path="/api/user/password" OR endpoint="password_change") AND status="failed" | stats count by user, src_ip | where count > 5