Memory safety bugs were reported in Thunderbird 45.5. Some of these bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code. This vulnerability affects Firefox < 50.1, Firefox ESR < 45.6, and Thunderbird < 45.6.
rhn.redhat.com/errata/RHSA-2016-2946.html
rhn.redhat.com/errata/RHSA-2016-2973.html
www.securityfocus.com/bid/94885
www.securitytracker.com/id/1037461
bugzilla.mozilla.org/buglist.cgi?bug_id=1319524%2C1298773%2C1299098%2C1309834%2C1312609%2C1313212%2C1317805%2C1312548%2C1315631%2C1287912
security.gentoo.org/glsa/201701-15
www.debian.org/security/2017/dsa-3757
www.mozilla.org/security/advisories/mfsa2016-94/
www.mozilla.org/security/advisories/mfsa2016-95/
www.mozilla.org/security/advisories/mfsa2016-96/