Appointment Booking Calendar <= 1.4.01 - Authenticated (Contributor+) Sensitive Information Exposure via 'id' Parameter

The Appointment Booking Calendar plugin for WordPress is vulnerable to Sensitive Information Exposure in versions up to, and including, 1.4.01. This is due to insufficient authorization and missing per-calendar ownership checks in the cpabc_appointments_calendar_load2() function, which is reachable via the cpabc_calendar_load2=1 query parameter in wp-admin and only checks is_admin() && current_user_can('edit_posts'), a capability available to Contributor-level users and above. This makes it possible for authenticated attackers with Contributor-level access and above to supply an arbitrary calendar ID via the id parameter and extract customer booking information, including email addresses, names, phone numbers, booking times, and comments, from any calendar managed by the plugin.