Executive brief
phpMyFAQ is a popular open-source FAQ management system used by organizations to build knowledge bases. An authentication bypass vulnerability allows attackers with access to a user's session to silently change account passwords—including administrator accounts—without verification of the current password. Once changed, the legitimate user is locked out, resulting in irreversible account takeover.
Technical details
This is a CWE-620 unverified password change vulnerability in the PUT /api/user/data/update endpoint. The vulnerable updateData() function verifies only the CSRF token and session ownership but does not call password_verify() to validate the current password before accepting a new one. An attacker with an active session and CSRF token can submit a JSON PUT request with a new password and confirmation, triggering $authDriver->update() to write a bcrypt hash without any current-password check. The attack requires network access, low-level privileges (any authenticated user), and no user interaction. Successful exploitation enables account takeover of any user including admins. phpMyFAQ 4.1.8 and later include patches; administrators should update immediately and consider invalidating all active sessions.
Affected products
- phpMyFAQ phpMyFAQ before 4.1.8
Timeline
- 2026-08-20: disclosed
- 2026-09-04: advisory
- 2026-09-04: patched: Version 4.1.8 patched