The forum module in NullLogic Groupware 1.2.7 allows remote authenticated users to cause a denial of service (application crash) by specifying (1) an empty string or (2) a non-numeric string when selecting a forum, related to the fmessagelist function.
http://www.vupen.com/english/advisories/2009/1817
http://www.securityfocus.com/archive/1/504737/100/0/threaded
http://www.nth-dimension.org.uk/utils/get.php?downloadsid=55