The Keychain implementation in Apple Mac OS X 10.6.8 and earlier does not properly handle an untrusted attribute of a Certification Authority certificate, which makes it easier for man-in-the-middle attackers to spoof arbitrary SSL servers via an Extended Validation certificate, as demonstrated by https access with Safari.
lists.apple.com/archives/security-announce/2012/Feb/msg00000.html
support.apple.com/kb/HT5130
www.computerworld.com/s/article/9219669/Mac_OS_X_can_t_properly_revoke_dodgy_digital_certificates
www.securityfocus.com/bid/49429
www.securitytracker.com/id?1026002
exchange.xforce.ibmcloud.com/vulnerabilities/69556