Vulnerability in Online Scheduling and Appointment Booking System – Bookly — CVE-2026-92799
What to do now
Update Online Scheduling and Appointment Booking System – Bookly to 28.3 or later.
Affected versions
- Everything up to and including 28.2
Affected: Online Scheduling and Appointment Booking System – Bookly (plugin, bookly-responsive-appointment-booking-tool)
What the vulnerability is
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.
Sources
- https://plugins.trac.wordpress.org/browser/bookly-responsive-appointment-booking-tool/tags/28.2/frontend/modules/booking/Ajax.php#L1447
- https://plugins.trac.wordpress.org/browser/bookly-responsive-appointment-booking-tool/tags/28.2/frontend/modules/booking/Ajax.php#L15
- https://plugins.trac.wordpress.org/browser/bookly-responsive-appointment-booking-tool/tags/28.2/frontend/modules/booking/Ajax.php#L785
- https://plugins.trac.wordpress.org/browser/bookly-responsive-appointment-booking-tool/tags/28.2/frontend/modules/booking/Ajax.php#L903
- https://plugins.trac.wordpress.org/browser/bookly-responsive-appointment-booking-tool/tags/28.2/lib/UserBookingData.php#L638
- https://plugins.trac.wordpress.org/browser/bookly-responsive-appointment-booking-tool/tags/28.2/lib/Validator.php#L276