Cross-site scripting (XSS) vulnerability in guestbook.php in Soren Boysen (SkullSplitter) PHP Guestbook 2.6 allows remote attackers to inject arbitrary web script or HTML via the url parameter.
https://exchange.xforce.ibmcloud.com/vulnerabilities/25293
http://www.vupen.com/english/advisories/2006/0974
http://www.securityfocus.com/bid/17136
http://www.securityfocus.com/archive/1/429254/100/0/threaded
http://securityreason.com/securityalert/650
http://secunia.com/advisories/19268