Security Vulnerabilities fixed in Thunderbird 115.6 — Mozilla

When processing a PGP/MIME payload that contains digitally signed text, the first paragraph of the text was never shown to the user. This is because the text was interpreted as a MIME message and the first paragraph was always treated as an email header section. A digitally signed text from a different context, such as a signed GIT commit, could be used to spoof an email message.
The signature of a digitally signed S/MIME email message may optionally specify the signature creation date and time. If present, Thunderbird did not compare the signature creation date with the message date and time, and displayed a valid signature despite a date or time mismatch. This could be used to give recipients the impression that a message was sent at a different date or time.
The WebGL DrawElementsInstanced method was susceptible to a heap buffer overflow when used on systems with the Mesa VM driver. This issue could allow an attacker to perform remote code execution and sandbox escape.
When resolving a symlink, a race may occur where the buffer passed to readlink may actually be smaller than necessary. This bug only affects Thunderbird on Unix-based operating systems (Android, Linux, MacOS). Windows is unaffected.
Thunderbird was susceptible to a heap buffer overflow in nsTextFragment due to insufficient OOM handling.
A use-after-free condition affected TLS socket creation when under memory pressure.
The VideoBridge allowed any content process to use textures produced by remote decoders. This could be abused to escape the sandbox.
The nsWindow::PickerOpen(void) method was susceptible to a heap buffer overflow when running in headless mode.
A use-after-free was identified in the nsDNSService::Init. This issue appears to manifest rarely during start-up.
The ShutdownObserver() was susceptible to potentially undefined behavior due to its reliance on a dynamic type that lacked a virtual destructor.
Memory safety bugs present in Firefox 120, Firefox ESR 115.5, and Thunderbird 115.5. 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.