CVE 2016-9893
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.
See the 
CVE page on Mitre.org
for more details.
