CE21 Suite 2.2.1 - 2.3.1 - Missing Authorization to Unauthenticated Privilege Escalation via Plugin Settings Update

The CE21 Suite plugin for WordPress is vulnerable to unauthorized plugin settings update due to a missing capability check on the wp_ajax_nopriv_ce21_single_sign_on_save_api_settings AJAX action in versions 2.2.1 to 2.3.1. This makes it possible for unauthenticated attackers to update the plugin's API settings including a secret key used for authentication. This allows unauthenticated attackers to create new admin accounts on an affected site.