CVE-2025-43931
📋 TL;DR
This vulnerability allows attackers to take over user accounts in Flask Boilerplate applications by exploiting the password reset feature. Attackers can manipulate the Host HTTP header to generate password reset links pointing to attacker-controlled servers, enabling them to intercept reset tokens. Any application using Flask Boilerplate with SERVER_NAME unconfigured is affected.
💻 Affected Systems
- flask-boilerplate
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of all user accounts, including administrative accounts, leading to full system takeover, data theft, and potential lateral movement within the network.
Likely Case
Targeted account takeover of specific users, potentially leading to unauthorized access to sensitive data, privilege escalation, and session hijacking.
If Mitigated
Limited impact with proper monitoring and detection, potentially allowing quick response to reset token misuse before account compromise.
🎯 Exploit Status
Exploitation requires network access to the application and ability to trigger password reset requests.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not available
Vendor Advisory: Not available
Restart Required: Yes
Instructions:
1. Update to a version beyond commit a170e7c if available. 2. Configure SERVER_NAME in Flask app configuration. 3. Ensure password reset URLs use absolute paths rather than relying on Host header.
🔧 Temporary Workarounds
Configure SERVER_NAME
allExplicitly set SERVER_NAME in Flask configuration to prevent reliance on Host header
export SERVER_NAME='yourdomain.com'
Or set in app.config['SERVER_NAME'] = 'yourdomain.com'
Disable password reset feature
allTemporarily disable password reset functionality until proper fix is implemented
Comment out password reset routes in user.py
🧯 If You Can't Patch
- Implement network-level controls to filter or validate Host headers
- Enable detailed logging of all password reset attempts and monitor for suspicious patterns
🔍 How to Verify
Check if Vulnerable:
Check if SERVER_NAME is configured in Flask app config and verify password reset URLs use absolute pathsCheck Version:
git log --oneline -1Verify Fix Applied:
Test password reset functionality with manipulated Host headers to ensure reset links point to correct domain📡 Detection & Monitoring
Log Indicators:
- Multiple password reset requests from same IP
- Password reset requests with unusual Host headers
- Failed login attempts followed by password reset requests
Network Indicators:
- HTTP requests with manipulated Host headers to password reset endpoints
- Unusual traffic patterns to password reset URLs
SIEM Query:
source="web_logs" AND (uri_path="/reset-password" OR uri_path="/password-reset") AND (host_header!="expected-domain.com" OR host_header contains suspicious patterns)