Security Vulnerabilities fixed in Thunderbird 78.11 — Mozilla

A locally-installed hostile program could send WM_COPYDATA messages that Thunderbird would processing incorrectly, leading to an out-of-bounds read. This bug only affects Thunderbird on Windows. Other operating systems are unaffected.
Mozilla developers Gabriele Svelto, Anny Gakhokidze, Alexandru Michis, Christian Holler reported memory safety bugs present in Thunderbird 78.11. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code.