Booking Package < 1.7.17 - Authenticated (Editor+) Privilege Escalation via Account Takeover to updateUser AJAX Action

Description

The Booking Package plugin for WordPress is vulnerable to Privilege Escalation via Account Takeover in versions up to, and including, 1.7.16. This is due to a missing capability check on the 'updateUser' branch of the package_app_action AJAX endpoint, where the handler only validates a nonce and the dispatcher invokes Schedule::updateUser() with the $administrator argument hard-coded to 1, bypassing the only owner-restriction check inside that function and allowing the target user to be determined solely by attacker-supplied input passed directly to wp_update_user(). This makes it possible for authenticated attackers, with Editor-level access and above, to change the email address and password of any account, including Administrator accounts, resulting in a full site takeover.