The EventPrime plugin for WordPress is vulnerable to unauthorized post modification due to missing authorization checks in all versions up to, and including, 4.2.8.4. This is due to the save_frontend_event_submission function accepting a user-controlled event_id parameter and updating the corresponding event post without enforcing ownership or capability checks. This makes it possible for authenticated (Customer+) attackers to modify posts created by administrators by manipulating the event_id parameter granted they can obtain a valid nonce.