Thunderbird unexpectedly enabled JavaScript in the composition area. The JavaScript execution context was limited to this area and did not receive chrome-level privileges, but could be used as a stepping stone to further an attack with other vulnerabilities. This vulnerability affects Thunderbird < 91.4.0.
https://www.mozilla.org/security/advisories/mfsa2021-54/
https://www.debian.org/security/2022/dsa-5034
https://security.gentoo.org/glsa/202208-14
https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html