FoodBook Lite <= 1.5.6 - Missing Authorization to Unauthenticated User Registration via 'registration_action' AJAX Action

The FoodBook Lite - Online Food Ordering System plugin for WordPress is vulnerable to Missing Authorization in all versions up to, and including, 1.5.6. The registration() function, accessible via the wp_ajax_nopriv_registration_action AJAX action, lacks any nonce verification or capability check, and does not check the WordPress users_can_register option before calling wp_insert_user(). This makes it possible for unauthenticated attackers to create new user accounts with the 'customer' role and receive authentication cookies, even when the site administrator has explicitly disabled user registration.