The Court Reservation WordPress plugin before 1.12.4 does not perform any authorisation or nonce verification on one of its challenge-management actions, allowing unauthenticated users to delete arbitrary tournament-ladder challenge records, along with the linked court-booking event when one was scheduled.
https://wpscan.com/vulnerability/0f4186c3-a5b5-4b03-ba1f-2e2ce11c21dc/