The Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin for WordPress is vulnerable to Sensitive Information Exposure in all versions up to, and including, 1.6.9.16. This is due to the plugin exposing its admin embed endpoint at `/wp-json/ssa/v1/embed-inner-admin` without authentication, which leaks plugin settings including staff names, business names, and configuration data that are not publicly displayed on the booking form. This makes it possible for unauthenticated attackers to extract private business configuration. In premium versions with integrations configured, this might also expose other sensitive data including API keys for external services.