Input validation

PHP-Fusion 6.00.306 and earlier, running under Apache HTTP Server 1.3.27 and PHP 4.3.3, allows remote authenticated users to upload files of arbitrary types using a filename that contains two or more extensions that ends in an assumed-valid extension such as .gif, which bypasses the validation, as demonstrated by uploading then executing an avatar file that ends in “.php.gif” and contains PHP code in EXIF metadata.