Vvveb before version 1.0.8.2 contains an unrestricted file upload vulnerability in the media upload handler that allows authenticated users with media-upload permissions to bypass extension restrictions by uploading a .htaccess file to map .phtml extensions to the PHP handler. Attackers can upload a .phtml file containing arbitrary PHP code and trigger execution by sending an unauthenticated HTTP GET request to the uploaded file, resulting in remote code execution with web server privileges.
