Security Vulnerabilities fixed in Thunderbird 78.13 — Mozilla

A suspected race condition when calling getaddrinfo led to memory corruption and a potentially exploitable crash. Note: This issue only affected Linux operating systems. Other operating systems are unaffected.
Thunderbird incorrectly treated an inline list-item element as a block element, resulting in an out of bounds read or memory corruption, and a potentially exploitable crash.
Instruction reordering resulted in a sequence of instructions that would cause an object to be incorrectly considered during garbage collection. This led to memory corruption and a potentially exploitable crash.
Uninitialized memory in a canvas object could have caused an incorrect free() leading to memory corruption and a potentially exploitable crash.
A use-after-free vulnerability in media channels could have led to memory corruption and a potentially exploitable crash.
Mozilla developers Christoph Kerschbaumer, Simon Giesecke, Sandor Molnar, and Olli Pettay reported memory safety bugs present in Thunderbird 78.12. 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.