The AcyMailing – An Ultimate Newsletter Plugin and Marketing Automation Solution for WordPress plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in the acym_extractArchive function in all versions up to, and including, 9.7.2. This makes it possible for authenticated attackers, with Subscriber-level access and above, to upload arbitrary files on the affected site's server which may make remote code execution possible.
When subscribing using AcyMailing, the 'redirect' parameter isn't properly sanitized. Turning the request from POST to GET, an attacker can craft a link containing a potentially malicious landing page and send it to the victim.