firefox is vulnerable to remote code execution. The vulnerability exists due to a memory corruption allowing an attacker to execute scripts on the system.
bugzilla.mozilla.org/buglist.cgi?bug_id=1606864%2C1712671%2C1730048%2C1735152
lists.debian.org/debian-lts-announce/2021/12/msg00030.html
lists.debian.org/debian-lts-announce/2022/01/msg00001.html
security-tracker.debian.org/tracker/CVE-2021-43534
www.debian.org/security/2021/dsa-5026
www.debian.org/security/2022/dsa-5034
www.mozilla.org/security/advisories/mfsa2021-48/
www.mozilla.org/security/advisories/mfsa2021-49/
www.mozilla.org/security/advisories/mfsa2021-50/