CFNetwork in Apple iOS before 8.3 and Apple OS X before 10.10.3 does not properly handle cookies during processing of redirects in HTTP responses, which allows remote attackers to bypass the Same Origin Policy via a crafted web site.
https://support.apple.com/HT204661
https://support.apple.com/HT204659
http://www.securitytracker.com/id/1032048
http://www.securityfocus.com/bid/73984
http://lists.apple.com/archives/security-announce/2015/Apr/msg00002.html
http://lists.apple.com/archives/security-announce/2015/Apr/msg00001.html