Simply Schedule Appointments <= 1.6.12.32 - Missing Authorization to Unauthenticated Sensitive Information Exposure and Arbitrary Appointment Deletion via 'recursive' Parameter on the appointment_types REST Endpoint via Public Nonce

The Simply Schedule Appointments plugin for WordPress is vulnerable to Sensitive Information Exposure in all versions up to, and including, 1.6.12.32 via the 'recursive' parameter. This makes it possible for unauthenticated attackers to extract customer PII — including names, email addresses, phone numbers, and custom form field data — stored in appointment records, as well as per-appointment public_token values. The leaked per-appointment public_token values also enable unauthenticated attackers to delete arbitrary appointments via the DELETE /wp-json/ssa/v1/appointments/{id} endpoint, which accepts the token as sole authorization.