CVE-2025-52576
📋 TL;DR
This vulnerability in Kanboard allows attackers to enumerate valid usernames and bypass IP-based brute-force protection mechanisms. By analyzing login behavior and manipulating HTTP headers, attackers can identify real user accounts and circumvent rate-limiting controls. Organizations running publicly accessible Kanboard instances with IP-based protections like Fail2Ban are particularly affected.
💻 Affected Systems
- Kanboard
📦 What is this software?
Kanboard by Kanboard
⚠️ Risk & Real-World Impact
Worst Case
Attackers successfully enumerate all valid usernames and bypass all rate-limiting to conduct credential stuffing attacks, potentially compromising all user accounts and gaining unauthorized access to sensitive project management data.
Likely Case
Attackers identify valid usernames and bypass some rate-limiting controls, increasing the success rate of brute-force attacks against known accounts, leading to some account compromises.
If Mitigated
With proper monitoring and additional authentication controls, the impact is limited to failed login attempts and potential username disclosure without successful account compromise.
🎯 Exploit Status
Exploitation requires access to the login page but no authentication. Attack involves analyzing login response differences and manipulating HTTP headers like X-Forwarded-For.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.2.46
Vendor Advisory: https://github.com/kanboard/kanboard/security/advisories/GHSA-qw57-7cx6-wvp7
Restart Required: Yes
Instructions:
1. Backup your Kanboard installation and database. 2. Download Kanboard version 1.2.46 or newer from the official repository. 3. Replace your current installation with the patched version. 4. Restart your web server (Apache/Nginx) and PHP service. 5. Verify the update by checking the version in the Kanboard interface.
🔧 Temporary Workarounds
Implement Web Application Firewall Rules
linuxConfigure WAF rules to block suspicious login patterns and header manipulation attempts.
# Example ModSecurity rule to detect header manipulation
SecRule REQUEST_HEADERS:X-Forwarded-For "@rx \d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}" \
"id:1001,phase:1,deny,status:403,msg:'Suspicious X-Forwarded-For header'"
# Rate limiting rule for login attempts
SecRule REQUEST_URI "@streq /?controller=AuthController&action=check" \
"id:1002,phase:1,pass,nolog,auditlog,setvar:tx.login_attempts=+1,expirevar:tx.login_attempts=300" \
SecRule TX:LOGIN_ATTEMPTS "@gt 10" \
"id:1003,phase:1,deny,status:429,msg:'Too many login attempts'"
# Block enumeration attempts
SecRule RESPONSE_BODY "@rx (Invalid credentials|User not found)" \
"id:1004,phase:4,deny,status:403,msg:'Potential username enumeration detected'"
Enable Multi-Factor Authentication
allRequire MFA for all user accounts to mitigate the risk of successful credential attacks.
# Enable MFA in Kanboard configuration
# Edit config.php and add:
$config['mfa']['enabled'] = true;
$config['mfa']['required'] = true;
# Or enable via database:
# UPDATE settings SET value = '1' WHERE option = 'mfa_enabled';
🧯 If You Can't Patch
- Implement network-level rate limiting using tools like Fail2Ban with additional header validation to detect spoofing attempts.
- Deploy Kanboard behind a reverse proxy that strips or validates X-Forwarded-For and similar headers before they reach the application.
🔍 How to Verify
Check if Vulnerable:
Check your Kanboard version by logging in as admin and navigating to Settings > About. If version is below 1.2.46, you are vulnerable. Alternatively, check the response differences between valid and invalid username login attempts.Check Version:
grep -r "APP_VERSION" /path/to/kanboard/ | head -1Verify Fix Applied:
After updating to 1.2.46, test that login attempts with invalid usernames return consistent response times and messages regardless of username validity. Verify that IP-based rate limiting cannot be bypassed via header manipulation.📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts with varying X-Forwarded-For headers from same source IP
- Login attempts with consistent timing patterns suggesting username enumeration
- Failed logins that bypass expected rate-limiting thresholds
Network Indicators:
- Unusual volume of POST requests to /?controller=AuthController&action=check
- Requests containing manipulated X-Forwarded-For headers from external IPs
SIEM Query:
source="kanboard_access.log" (method="POST" uri="/?controller=AuthController&action=check") | stats count by src_ip, http_x_forwarded_for | where count > 10🔗 References
- https://github.com/kanboard/kanboard/blob/cbb7e60fb595ff4572bb8801b275a0b451c4bda0/app/Model/UserLockingModel.php#L101-L104
- https://github.com/kanboard/kanboard/blob/cbb7e60fb595ff4572bb8801b275a0b451c4bda0/app/Subscriber/AuthSubscriber.php#L96-L108
- https://github.com/kanboard/kanboard/commit/3079623640dc39f9c7b0c840d2a79095331051f1
- https://github.com/kanboard/kanboard/security/advisories/GHSA-qw57-7cx6-wvp7
- https://github.com/kanboard/kanboard/security/advisories/GHSA-qw57-7cx6-wvp7
