The Online Scheduling and Appointment Booking System – Bookly plugin for WordPress is vulnerable to Authorization Bypass via PHP Type Juggling in all versions up to, and including, 28.2

Overview

The Online Scheduling and Appointment Booking System – Bookly plugin for WordPress is vulnerable to Authorization Bypass via PHP Type Juggling in all versions up to, and including, 28.2. This is due to the postValidateCustomer() function using a loose PHP inequality operator (!=) to compare the session-stored one-time verification code against the attacker-supplied verification_code parameter — a flaw that is further exposed by the booking AJAX controller registering all its methods as wp_ajax_nopriv_ handlers and unconditionally overriding csrfTokenValid() to return true, leaving the endpoint both unauthenticated and CSRF-unprotected. This makes it possible for unauthenticated attackers to bypass the phone/email ownership verification step and overwrite the name, email, phone, and address fields of any arbitrary existing Bookly customer record, redirecting that customer's booking notifications to attacker-controlled contact details. The bypass is achievable because the json_data input channel decodes input via json_decode(), which preserves real PHP types and causes the wp_kses filter to leave non-string values such as the JSON boolean true untouched; submitting true as the verification_code satisfies the loose comparison against the session's non-zero integer code (generated by mt_rand(100000, 999999)), causing true != <non-zero int> to evaluate as false and the guard to be bypassed.

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.