PZ Frontend Manager <= 1.0.6 - Missing Authorization to Arbitrary User Deletion via 'dataType' Parameter

Summary

The PZ Frontend Manager plugin for WordPress is vulnerable to Missing Authorization in all versions up to and including 1.0.6. The pzfm_user_request_action_callback() function, registered via the wp_ajax_pzfm_user_request_action action hook, lacks both capability checks and nonce verification. This function handles user activation, deactivation, and deletion operations. When the 'dataType' parameter is set to 'delete', the function calls wp_delete_user() on all provided user IDs without verifying that the current user has the appropriate permissions. Notably, the similar pzfm_remove_item_callback() function does check pzfm_can_delete_user() before performing deletions, indicating this was an oversight. This makes it possible for authenticated attackers, with Subscriber-level access and above, to delete arbitrary WordPress users (including administrators) by sending a crafted request to the AJAX endpoint.