The Firefox Health Reports (aka FHR or about:healthreport) feature in Mozilla Firefox before 46.0 does not properly restrict the origin of events, which makes it easier for remote attackers to modify sharing preferences by leveraging access to the remote-report IFRAME element.
https://security.gentoo.org/glsa/201701-15
https://bugzilla.mozilla.org/show_bug.cgi?id=870870
http://www.ubuntu.com/usn/USN-2936-3
http://www.ubuntu.com/usn/USN-2936-2
http://www.ubuntu.com/usn/USN-2936-1
http://www.securitytracker.com/id/1035692
http://www.mozilla.org/security/announce/2016/mfsa2016-48.html
http://lists.opensuse.org/opensuse-updates/2016-05/msg00038.html
http://lists.opensuse.org/opensuse-security-announce/2016-05/msg00005.html