The Appointment Booking and Scheduling Calendar Plugin – WP Timetics plugin for WordPress is vulnerable to unauthorized access and modification of data due to a missing capability check on the update and register_routes functions in all versions up to, and including, 1.0.36. This makes it possible for unauthenticated attackers to view and modify booking details.
https://plugins.trac.wordpress.org/browser/timetics/tags/1.0.36/core/bookings/booking.php#L592
https://plugins.trac.wordpress.org/browser/timetics/tags/1.0.36/core/bookings/api-booking.php#L56