EventPrime < 4.2.8.5 - Missing Authorization to Authenticated (Subscriber+) Arbitrary Event Modification via 'event_id' Parameter

Description

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.