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.
arthur.barton.de/pipermail/ngircd-ml/2013-February/000623.html
arthur.barton.de/pipermail/ngircd-ml/2013-February/000625.html
lists.fedoraproject.org/pipermail/package-announce/2013-April/101706.html
ngircd.barton.de/doc/NEWS
secunia.com/advisories/52982
www.osvdb.com/show/osvdb/91836
arthur.barton.de/cgi-bin/gitweb.cgi?p=ngircd.git%3Bh=0e63fb3fa7ac4ca048e8c2b648d2be3fd0572311