irc-channel.c in ngIRCd before 0.10.3 allows remote attackers to cause a denial of service (crash) via a JOIN command without a channel argument.
http://www.securityfocus.com/bid/26489
http://secunia.com/advisories/27692
http://ngircd.barton.de/doc/ChangeLog
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=451875
http://arthur.barton.de/pipermail/ngircd-ml/2007-July/000292.html