The WatchTowerHQ plugin for WordPress is vulnerable to authentication bypass in versions up to, and including, 3.9.6. This is due to the watchtower_ota_token default value is empty, and the not empty check is missing in the Password_Less_Access::login function. This makes it possible for unauthenticated attackers to log in to the WatchTowerHQ client administrator user.
A product requires authentication, but the product has an alternate path or channel that does not require authentication.