The Reader mode feature in Mozilla Firefox before 37.0.1 on Android, and Desktop Firefox pre-release, does not properly handle privileged URLs, which makes it easier for remote attackers to execute arbitrary JavaScript code with chrome privileges by leveraging the ability to bypass the Same Origin Policy.
https://security.gentoo.org/glsa/201512-10
https://bugzilla.mozilla.org/show_bug.cgi?id=1147597
http://www.securitytracker.com/id/1032029
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
http://www.mozilla.org/security/announce/2015/mfsa2015-43.html