WPGYM <= 67.1.0 - Unauthenticated Arbitrary File Upload

The WPGYM - Wordpress Gym Management System plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in the MJ_gmgt_user_avatar_image_upload() function in all versions up to, and including, 67.1.0. This makes it possible for unauthenticated attackers to upload arbitrary files on the affected site's server which may make remote code execution possible.