AcyMailing <= 10.11.1 - Authenticated (Subscriber+) Missing Authorization to Account Takeover via Notification Template Update

The AcyMailing – An Ultimate Newsletter Plugin and Marketing Automation Solution for WordPress plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 10.11.1. This is due to the plugin not properly verifying that a user is authorized to perform an action. This makes it possible for authenticated attackers, with subscriber-level access and above, to overwrite the BCC field of the acy_notification_cms notification template, causing subsequent WordPress password-reset emails — including those targeting administrator accounts — to be silently copied to an attacker-controlled address, enabling account takeover via the captured reset link. Successful exploitation requires the site administrator to have enabled the "Send website emails with AcyMailing" option, which routes WordPress core notification emails through AcyMailing's templating system.