channel.c in ngIRCd 20 and 20.1 allows remote attackers to cause a denial of service (assertion failure and crash) via a KICK command for a user who is not on the associated channel.
http://www.osvdb.com/show/osvdb/91836
http://secunia.com/advisories/52982
http://ngircd.barton.de/doc/NEWS
http://lists.fedoraproject.org/pipermail/package-announce/2013-April/101706.html
http://arthur.barton.de/pipermail/ngircd-ml/2013-February/000625.html
http://arthur.barton.de/pipermail/ngircd-ml/2013-February/000623.html