Multiple cross-site scripting (XSS) vulnerabilities in FlatNuke 2.5.5 and possibly earlier versions allow remote attackers to inject arbitrary web script or HTML via the (1) bodycolor, (2) backimage, (3) theme, or (4) logo parameter to structure.php, (5) admin, (6) admin_mail, or (7) back parameter to footer.php, or (8) the message body in a news post.