Sulu is a PHP content management system. This vulnerability allows an attacker to inject arbitrary HTML/JavaScript code through the media download URL in Sulu CMS. It affects the SuluMediaBundle component. The vulnerability is a Reflected Cross-Site Scripting (XSS) issue, which could potentially allow attackers to steal sensitive information, manipulate the website's content, or perform actions on behalf of the victim. This vulnerability is fixed in 2.6.5 and 2.5.21.