AcyMailing 9.11.0 - 10.8.1 - Missing Authorization to Authenticated (Subscriber+) Privilege Escalation

Description

The AcyMailing plugin for WordPress is vulnerable to privilege escalation in all versions From 9.11.0 up to, and including, 10.8.1 due to a missing capability check on the `wp_ajax_acymailing_router` AJAX handler. This makes it possible for authenticated attackers, with Subscriber-level access and above, to access admin-only controllers (including configuration management), enable the autologin feature, create a malicious newsletter subscriber with an injected `cms_id` pointing to any WordPress user, and then use the autologin URL to authenticate as that user, including administrators.