A malicious webpage could have triggered a use-after-free, memory corruption, and a potentially exploitable crash. *This bug could only be triggered when accessibility was enabled.*. This vulnerability affects Thunderbird < 78.12, Firefox ESR < 78.12, and Firefox < 90.
https://www.mozilla.org/security/advisories/mfsa2021-30/
https://www.mozilla.org/security/advisories/mfsa2021-29/
https://www.mozilla.org/security/advisories/mfsa2021-28/
https://security.gentoo.org/glsa/202208-14