The security-ninja-premium WordPress plugin before 5.290 does not verify the second authentication factor in one of its two-factor authentication code paths, allowing an unauthenticated attacker who knows a users password to complete authentication without the one-time code and bypass enforced two-factor authentication for any account, including administrators. The affected two-factor module ships only in the premium build.
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.