CVE-2026-92238

CRITICAL 9.8

Ambiguous parsing of mail headers

CVSS Score

9.8

EPSS Score

0.2%

EPSS Percentile

8th

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.

Vendor	mozilla
Product	thunderbird
Ecosystems	Browser JavaScript
Industries	Technology
Published	Sep 15, 2026
Last Updated	Sep 22, 2026

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Affected Versions

Mozilla / Thunderbird

All versions affected

References

NVD ↗ CVE.org ↗ EPSS Data ↗

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

Credits

Ramesh Adhikari, Dr. Faruk Kazi (CoE-CNDS Lab, VJTI, Mumbai, India)