WebKit in Apple iOS before 9.2 and Safari before 9.0.2 misparses content extensions, which allows remote attackers to obtain sensitive browsing-history information via a crafted web site.
https://support.apple.com/kb/HT205636
https://support.apple.com/HT205639
https://support.apple.com/HT205635
http://www.securitytracker.com/id/1034341
http://www.securityfocus.com/bid/78722
http://lists.apple.com/archives/security-announce/2015/Dec/msg00003.html
http://lists.apple.com/archives/security-announce/2015/Dec/msg00000.html