The Bonjour functionality in mDNSResponder, iChat 3.1.6, and InstantMessage framework 428 in Apple Mac OS X 10.4.8 allows remote attackers to cause a denial of service (persistent application crash) via a crafted phsh hash attribute in a TXT key.
http://www.securitytracker.com/id?1017661
http://secunia.com/advisories/24198
http://secunia.com/advisories/23945
http://lists.apple.com/archives/Security-announce/2007/Feb/msg00000.html