A maliciously constructed mail header could lead to multiple fields being parsed as one, or potential memory safety violations. This vulnerability was fixed in Thunderbird 156, Thunderbird 140.16, and Thunderbird 153.3.
References 4
https://bugzilla.mozilla.org/show_bug.cgi?id=2060601
security@mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-94/
security@mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-95/
security@mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-96/
security@mozilla.org