csregprinter in the Printing component in Apple Mac OS X 10.4.11 and 10.5.6 does not properly handle error conditions, which allows local users to execute arbitrary code via unknown vectors that trigger a heap-based buffer overflow.
http://www.vupen.com/english/advisories/2009/0422
http://www.securityfocus.com/bid/33811
http://www.securityfocus.com/bid/33759
http://support.apple.com/kb/HT3438
http://secunia.com/advisories/33937
http://lists.apple.com/archives/security-announce/2009/Feb/msg00000.html