firefox is vulnerable to Information Disclosure vulnerability. An attacker could use a JavaScript Map/Set timing attack to determine whether an atom is used by another compartment/zone in specific contexts. This could be used to leak information, such as usernames embedded in JavaScript code, across websites.
rhn.redhat.com/errata/RHSA-2016-2946.html
www.securityfocus.com/bid/94885
www.securitytracker.com/id/1037461
access.redhat.com/errata/RHSA-2016:2946
access.redhat.com/security/updates/classification/#critical
bugzilla.mozilla.org/show_bug.cgi?id=1317936
security.gentoo.org/glsa/201701-15
www.debian.org/security/2017/dsa-3757
www.mozilla.org/en-US/security/known-vulnerabilities/firefox-esr/#firefoxesr45.6
www.mozilla.org/security/advisories/mfsa2016-94/
www.mozilla.org/security/advisories/mfsa2016-95/
www.mozilla.org/security/advisories/mfsa2016-96/