AI Engine < 3.3.3 - Editor+ Arbitrary File Upload

Description

The plugin is vulnerable to arbitrary file uploads due to missing file type validation in the `rest_helpers_update_media_metadata` function. This makes it possible for authenticated attackers, with Editor-level access and above, to upload arbitrary files on the affected site's server which may make remote code execution possible. The attacker can upload a benign image file, then use the `update_media_metadata` endpoint to rename it to a PHP file, creating an executable PHP file in the uploads directory.