The MDJM Event Management plugin for WordPress is vulnerable to Arbitrary File Upload in all versions up to, and including, 1.7.8.3 via the mdjm_send_comm_email function. This is due to no file type, extension, or MIME type validation being performed on uploaded files. This makes it possible for authenticated attackers, with administrator-level access and above, to upload files that may be executable, which makes remote code execution possible.