The page-loading implementation in WebKit, as used in Apple Safari before 6.2.6, 7.x before 7.1.6, and 8.x before 8.0.6, does not properly handle the rel attribute in an A element, which allows remote attackers to bypass the Same Origin Policy for a link's target, and spoof the user interface, via a crafted web site.
https://support.apple.com/HT204826
http://www.securitytracker.com/id/1032270
http://www.securityfocus.com/bid/74524
http://support.apple.com/kb/HT204941
http://lists.apple.com/archives/security-announce/2015/May/msg00000.html
http://lists.apple.com/archives/security-announce/2015/Jun/msg00001.html