LatePoint < 5.6.3 - Unauthenticated Insecure Direct Object Reference to Arbitrary Creation via 'service_id' Parameter

Description

The LatePoint – Calendar Booking Plugin for Appointments and Events plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 5.6.2 via the 'service_id' parameter due to missing validation on a user controlled key. This makes it possible for unauthenticated attackers to create approved bookings against services explicitly restricted to admins and agents, consuming restricted appointment capacity and triggering unauthorized bookings for admin/agent-only services. The bypass works via both the params[booking][service_id] parameter in steps__load_step and the presets[selected_service] parameter in steps__start, both of which are publicly accessible without authentication.