Integer underflow in the Lists_MakeMask() function in lists.c in ngIRCd before 0.8.2 allows remote attackers to cause a denial of service (application crash) and possibly execute arbitrary code via a long MODE line that causes an incorrect length calculation, which leads to a buffer overflow.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2005-0200
http://www.securityfocus.com/bid/12397
http://securitytracker.com/id?1013047
http://secunia.com/advisories/14059
http://secunia.com/advisories/14056
http://bugs.gentoo.org/show_bug.cgi?id=79705
http://arthur.ath.cx/pipermail/ngircd-ml/2005-January/000228.html