Drag and Drop Multiple File Upload for Contact Form 7 <= 1.3.9.0 - Directory Traversal via `wpcf7_guest_user_id` Cookie

The Drag and Drop Multiple File Upload for Contact Form 7 plugin for WordPress is vulnerable to Directory Traversal in all versions up to, and including, 1.3.9.0 via the wpcf7_guest_user_id cookie. This makes it possible for unauthenticated attackers to upload and delete files outside of the originally intended directory. The impact of this vulnerability is limited, as file types are validated and only safe ones can be uploaded, while deletion is limited to the plugin's uploads folder.