Multiple buffer overflows in iCloud Keychain in Apple iOS before 8.2 and Apple OS X through 10.10.2 allow man-in-the-middle attackers to execute arbitrary code by modifying the client-server data stream during keychain recovery.
https://support.apple.com/kb/HT204563
https://support.apple.com/HT204423
https://support.apple.com/HT204413
http://www.securitytracker.com/id/1031864
http://www.securityfocus.com/bid/73007
http://lists.apple.com/archives/security-announce/2015/Mar/msg00002.html
http://lists.apple.com/archives/security-announce/2015/Mar/msg00000.html