Online Scheduling and Appointment Booking System <= 28.2 - Unauthenticated Authorization Bypass via PHP Type Juggling via 'verification_code' Parameter Type Juggling via json_data

Summary

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.

Timeline

1. Sep 25, 2026, 6:39 AM UTCCVE published
2. Sep 25, 2026, 10:35 AM UTCCISA SSVC assessment

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

3. Sep 25, 2026, 10:37 AM UTCRecord last updated

Affected versions

• ladela Online Scheduling and Appointment Booking System – Bookly

  through 28.2

References 9