CVE-2026-92238

Ambiguous parsing of mail headers

State: Published
Severity: 9.8 Critical
Published: Sep 15, 2026
Updated: Sep 22, 2026
Reserved: Sep 15, 2026

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	9.8 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H	CISA-ADP

Weaknesses

CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Affected Products

Product	Versions
ThunderbirdMozilla	140.16 through 140.Not affected 153.3 through 153.Not affected 156 and laterNot affected

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2060601
https://www.mozilla.org/security/advisories/mfsa2026-94/
https://www.mozilla.org/security/advisories/mfsa2026-95/
https://www.mozilla.org/security/advisories/mfsa2026-96/

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