A directory traversal vulnerability exists in 35mm Slide Gallery, which allows an attacker to read arbitrary files on the server. This vulnerability is due to insufficient sanitization of user-supplied input to the 'imgdir' parameter in 'index.php'. An attacker can exploit this vulnerability by sending a specially crafted HTTP request containing directory traversal sequences (e.g. '../') to the vulnerable server. Successful exploitation of this vulnerability could result in the disclosure of sensitive information, such as system and application files.