CVE-2026-92238: Mozilla Thunderbird

Critical severity, CVSS 9.8. EPSS: 0.5% chance of exploitation in the next 30 days.

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.

Affected products

• Mozilla Thunderbird: before 140.16.0 (fixed in 140.16.0); from 141.0, before 153.3.0 (fixed in 153.3.0); from 154.0, before 156.0 (fixed in 156.0)

Published 2026-09-15. Last modified 2026-09-24.