Limit Login Attempts Reloaded < 3.4.1 - Two-Factor Authentication Bypass via Malformed X-Forwarded-For Header

The Limit Login Attempts Security WordPress plugin before 3.4.1 does not confirm that its two-factor authentication step succeeded before completing a login and treats a failure to build that step as success, so an attacker who holds a protected user's password can bypass the second factor by sending a request header that breaks the step.