Networking in Apple Mac OS X 10.6.2 through 10.6.4 allows remote attackers to cause a denial of service (NULL pointer dereference and system crash) via a crafted PIM packet.
http://www.vupen.com/english/advisories/2010/3046
http://www.securitytracker.com/id?1024723
http://support.apple.com/kb/HT4456
http://support.apple.com/kb/HT4435
http://secunia.com/advisories/42314
http://lists.apple.com/archives/security-announce/2010//Nov/msg00003.html
http://lists.apple.com/archives/security-announce/2010//Nov/msg00000.html