After releasing the Firefox
update to 126.96.36.199 early because of a serious security vulnerability the update for Thunderbird was released on schedule. The automatic update
routine is already suggesting to update Thunderbird to its newest version and the website
has been updated with the latest information as well.
The same security vulnerabilities that have been fixed in Firefox 188.8.131.52 have also been fixed in Thunderbird which means that you should update immediately to the latest version. As far as I can tell there are no new features in this version, at least all my extensions are still working fine.
The Rumbling Edge lists the following three fixes
for Thunderbird 184.108.40.206
Fixed: MFSA 2007-27 - Unescaped URIs passed to external programs
Fixed: MFSA 2007-26 - Privilege escalation through chrome-loaded about
Fixed: 389106 - firefox may not escape quotes everywhere.