Cross-site scripting (XSS) vulnerability in index.php in myPHP Guestbook 2.0.4 and earlier allows remote attackers to inject arbitrary web script or HTML via the lang parameter.
https://exchange.xforce.ibmcloud.com/vulnerabilities/27074
http://www.vupen.com/english/advisories/2006/2308
http://www.securityfocus.com/archive/1/436842/100/0/threaded