Appointment Booking Calendar <= 1.6.9.29 - Missing Authorization to Unauthenticated Sensitive Information Exposure via Settings REST API Endpoint

Summary

The Appointment Booking Calendar — Simply Schedule Appointments plugin for WordPress is vulnerable to unauthorized access of sensitive data in all versions up to and including 1.6.9.29. This is due to two compounding weaknesses: (1) a non-user-bound `public_nonce` is exposed to unauthenticated users through the public `/wp-json/ssa/v1/embed-inner` REST endpoint, and (2) the `get_item()` method in `SSA_Settings_Api` relies on `nonce_permissions_check()` for authorization (which accepts the public nonce) but does not call `remove_unauthorized_settings_for_current_user()` to filter restricted fields. This makes it possible for unauthenticated attackers to access admin-only plugin settings including the administrator email, phone number, internal access tokens, notification configurations, and developer settings via the `/wp-json/ssa/v1/settings/{section}` endpoint. The exposure of appointment tokens also allows an attacker to modify or cancel appointments.

Timeline

1. Mar 13, 2026, 7:23 AM UTCCVE published
2. Mar 13, 2026, 4:06 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: partial

3. Apr 8, 2026, 4:54 PM UTCRecord last updated

Affected versions

• croixhaug Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin

  through 1.6.9.29

References 5