The Page Loading implementation in WebKit in Apple iOS before 9.3 and Safari before 9.1 mishandles HTTP responses with a 3xx (aka redirection) status code, which allows remote attackers to spoof the displayed URL, bypass the Same Origin Policy, and obtain sensitive cached information via a crafted web site.
http://lists.apple.com/archives/security-announce/2016/Mar/msg00000.html
http://lists.apple.com/archives/security-announce/2016/Mar/msg00005.html
https://support.apple.com/HT206166