The Certificate Trust Policy component in Apple Mac OS X before 10.6.8 does not perform CRL checking for Extended Validation (EV) certificates that lack OCSP URLs, which might allow man-in-the-middle attackers to spoof an SSL server via a revoked certificate.
http://support.apple.com/kb/HT4723
http://lists.apple.com/archives/security-announce/2011//Jun/msg00000.html