CVE-2019-9816

A possible vulnerability exists where type confusion can occur when manipulating JavaScript objects in object groups, allowing for the bypassing of security checks within these groups. *Note: this vulnerability has only been demonstrated with UnboxedObjects, which are disabled by default on all supported releases.*. This vulnerability affects Thunderbird < 60.7, Firefox < 67, and Firefox ESR < 60.7.

Source: CVE-2019-9816