core/dom/Document.cpp in Blink, as used in Google Chrome before 43.0.2357.65, enables the inheritance of the designMode attribute, which allows remote attackers to bypass the Same Origin Policy by leveraging the availability of editing.
https://src.chromium.org/viewvc/blink?revision=192658&view=revision
https://security.gentoo.org/glsa/201506-04
https://code.google.com/p/chromium/issues/detail?id=444927
http://www.securitytracker.com/id/1032375
http://www.securityfocus.com/bid/74723
http://www.debian.org/security/2015/dsa-3267
http://lists.opensuse.org/opensuse-updates/2015-11/msg00015.html
http://lists.opensuse.org/opensuse-updates/2015-05/msg00091.html
http://googlechromereleases.blogspot.com/2015/05/stable-channel-update_19.html