Cross-site scripting (XSS) vulnerability in index.php in @lex Guestbook 4.0.1 allows remote attackers to inject arbitrary web script or HTML via the skin parameter.
https://exchange.xforce.ibmcloud.com/vulnerabilities/30639
http://www.vupen.com/english/advisories/2006/4807
http://www.securityfocus.com/bid/21373
http://www.securityfocus.com/archive/1/453123/100/0/threaded