The Booking Calendar and Notification plugin for WordPress is vulnerable to unauthorized access, modification, and loss of data due to missing capability checks on the wpcballbookings(), wpcbupdatebookingpost(), and wpcbdeleteposts() functions in all versions up to, and including, 4.0.3. This makes it possible for unauthenticated attackers to extract data, create or update bookings, or delete arbitrary posts.