Cross-site scripting (XSS) vulnerability in export_handler.php in WebCalendar 1.0.4 and earlier allows remote attackers to inject arbitrary web script or HTML via the format parameter.
http://www.vupen.com/english/advisories/2006/5067
http://www.securityfocus.com/archive/1/454810/100/0/threaded
http://www.debian.org/security/2007/dsa-1279
http://securityreason.com/securityalert/2054