CVE-2026-85590: phpMyFAQ before 4.1.8 Authentication Bypass via Two-Factor Disable

Vulnerability summary

CVE-2026-85590 is a high (CVSS 7.1) Use of Single-factor Authentication vulnerability in thorsten phpmyfaq. EPSS estimates a 0.52% chance of exploitation in the next 30 days, higher than 43.1% of scored vulnerabilities.

Timeline

1. 04-09-2026
   PublishedVulnerability first disclosed.
2. 04-09-2026
   Last modifiedVulnerability information updated.

Description

phpMyFAQ before 4.1.8 contains an authentication bypass vulnerability in its two-factor authentication (TOTP) disable functionality. The removeTwofactorConfig() handler (reachable via POST /api/user/remove-twofactor) verifies only that the user is logged in and that a valid CSRF token is supplied, then disables TOTP without requiring password re-entry or a current TOTP code. The same downgrade is also reachable inline via PUT /api/user/data/update, which accepts a plain twofactor_enabled form field under the same session+CSRF-only guard. An attacker who has hijacked a user's session can silently strip two-factor protection from any account, including administrator accounts, after which password-only authentication succeeds.

• CWE-308Use of Single-factor AuthenticationThe product uses an authentication algorithm that uses a single factor (e.g., a password) in a security context that should require more than one factor.