Import and export users and customers <= 2.4.0 - Missing Authorization to Authenticated (Subscriber+) Sensitive Information Exposure via email_template_selected AJAX Action

The Import and export users and customers plugin for WordPress is vulnerable to Sensitive Information Exposure in all versions up to, and including, 2.4.0 via the email_template_selected. This makes it possible for authenticated attackers, with subscriber-level access and above, to extract the post_title and raw post_content of arbitrary posts regardless of status (draft, private, future, trash, password-protected) or post type (including non-public CPTs such as WooCommerce orders and internal CRM records) by enumerating post IDs. The required codection-security nonce is exposed as inline JavaScript on any wp-admin page when ?post_type=acui_email_template is appended to the URL, which is reachable by any authenticated user including Subscribers.