Contact Form 7 Drag and Drop Multiple File Upload - Arbitrary File Upload

The Drag and Drop Multiple File Upload for Contact Form 7 plugin for WordPress is vulnerable to arbitrary file uploads due to insufficient file type validation in all versions up to, and including, 1.3.8.9. This makes it possible for unauthenticated attackers to bypass the plugin's blacklist and upload .phar or other dangerous file types on the affected site's server, which may make remote code execution possible on the servers that are configured to handle .phar files as executable PHP scripts, particularly in default Apache+mod_php configurations where the file extension is not strictly validated before being passed to the PHP interpreter.