Apple Mac EFI before 2015-001, as used in OS X before 10.10.4 and other products, does not enforce a locking protection mechanism upon being woken from sleep, which allows local users to conduct EFI flash attacks by leveraging root privileges.
http://www.securitytracker.com/id/1032444
http://www.securityfocus.com/bid/75495
http://support.apple.com/kb/HT204942
http://support.apple.com/kb/HT204934
http://lists.apple.com/archives/security-announce/2015/Jun/msg00003.html
http://lists.apple.com/archives/security-announce/2015/Jun/msg00002.html