CVE-2026-92238 Thunderbird - Memory Safety Violation

Thunderbird contains a mail header parsing vulnerability caused by maliciously constructed headers, letting attackers cause memory safety violations or merge multiple fields, exploit requires crafted mail headers.

CVSS base score 9.8 /10
Critical
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.54% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Memory Safety Violation
Impact
Denial Of Service
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
15 September 2026
Updated
15 October 2026
Weakness
CWE-444

Vendor fix

Update to Thunderbird 156 or Thunderbird 140.16.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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