includes/functions.php in Craig Knudsen WebCalendar before 1.0.5 does not protect the noSet variable from external modification, which allows remote attackers to set arbitrary global variables via a URL with modified values in the noSet parameter, which leads to resultant vulnerabilities that probably include remote file inclusion and other issues.
secunia.com/advisories/24403
secunia.com/advisories/24519
sourceforge.net/mailarchive/forum.php?thread_id=31840112&forum_id=46247
sourceforge.net/project/shownotes.php?group_id=3870&release_id=491130
webcalendar.cvs.sourceforge.net/webcalendar/webcalendar/includes/functions.php?r1=1.211.2.7&r2=1.211.2.8
webcalendar.cvs.sourceforge.net/webcalendar/webcalendar/includes/functions.php?view=log
www.debian.org/security/2007/dsa-1267
www.securityfocus.com/bid/22834
www.vupen.com/english/advisories/2007/0851
exchange.xforce.ibmcloud.com/vulnerabilities/32832