Appointment Booking Plugin <= 5.7.3 - Authenticated (Subscriber+) Sensitive Information Exposure in 'first_name' Parameter Template Re-expansion

The Appointment Booking Plugin – LatePoint | Calendar & Scheduling for WordPress plugin for WordPress is vulnerable to Sensitive Information Exposure in all versions up to, and including, 5.7.3 via the 'params[customer][first_name]' parameter. This makes it possible for authenticated attackers, with subscriber-level access and above, to extract privileged booking data including the administrator-only admin_notes field, assigned agent internal contact details, transaction tokens, and payment request URLs delivered via rendered notification emails. A LatePoint customer can exploit this by storing a template placeholder such as {{customer_admin_notes}} in their own first_name field via the customer_cabinet__update route, then triggering the password-reset email flow to receive the expanded value in the resulting notification.