firefox is vulnerable to arbitrary code execution. A type confusion bug occurs when using logical assignment operators in JavaScript switch statements.
bugzilla.mozilla.org/show_bug.cgi?id=1684020
security-tracker.debian.org/tracker/CVE-2021-23954
www.mozilla.org/en-US/security/advisories/mfsa2021-03/#CVE-2021-23954
www.mozilla.org/security/advisories/mfsa2021-03/
www.mozilla.org/security/advisories/mfsa2021-04/
www.mozilla.org/security/advisories/mfsa2021-05/