The document.cookie API implementation in the CFNetwork Cookies subsystem in WebKit in Apple iOS before 9 allows remote attackers to bypass an intended single-cookie restriction via unspecified vectors.
http://lists.apple.com/archives/security-announce/2015/Sep/msg00001.html
http://lists.apple.com/archives/security-announce/2015/Sep/msg00007.html
https://support.apple.com/HT205212