An unrestricted file upload vulnerability in dulldusk/phpfm through 1.8.0 allows an unauthenticated remote attacker to execute arbitrary PHP code on the server. The application ships with an empty upload extension filter ($upload_ext_filter = array()) and no authentication enabled by default (auth_pass is empty string), allowing an unauthenticated attacker to upload a PHP webshell and execute it by browsing to the uploaded path.