Vulnerability Description
Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
CVSS Score
9.1
CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Thunderbird | < 140.15.0 |
Related Weaknesses (CWE)
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2061087Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2026-86/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-87/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-88/Vendor Advisory
FAQ
What is CVE-2026-84639?
CVE-2026-84639 is a vulnerability with a CVSS score of 9.1 (CRITICAL). Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
How severe is CVE-2026-84639?
CVE-2026-84639 has been rated CRITICAL with a CVSS base score of 9.1/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-84639?
Check the references section above for vendor advisories and patch information. Affected products include: Mozilla Thunderbird.