YITH WooCommerce Waitlist Premium <= 3.35.0 - Authenticated (Subscriber+) Privilege Escalation to Admin via wp_ajax_yith_wcwtl_add_user

The YITH WooCommerce Waitlist Premium plugin for WordPress is vulnerable to Privilege Escalation in versions up to, and including, 3.35.0. This is due to the add_user_in_waiting_list() function registered on the wp_ajax_yith_wcwtl_add_user action being missing both a capability check and a nonce verification, and using parse_str() + extract() to import attacker-controlled variables from $_POST['params'] that are then passed to wp_create_user() and $user->set_role(). This makes it possible for authenticated attackers, with Subscriber-level access and above, to elevate their privileges to that of an administrator by creating a new user account and assigning it the administrator role.