The Hydra Booking — Appointment Scheduling & Booking Calendar plugin for WordPress is vulnerable to unauthorized booking cancellation in all versions up to, and including, 1.1.27. This is due to the plugin's "tfhb_meeting_form_submit_callback" function using insufficiently random values to generate booking cancellation tokens, combined with a globally shared nonce. This makes it possible for unauthenticated attackers to cancel arbitrary bookings via brute force attacks against the tfhb_meeting_form_cencel AJAX endpoint.
