Name: CVE-2026-84640: Buffer Over-read
Creator: Rapid7
Published: 2026-09-01T00:00:00.000Z
License: https://www.rapid7.com/legal/website-terms-of-use/
Keywords: CVE, CVE-2026-84640, CWE-126, CVSS 7.5, EPSS 0.00263

A maliciously constructed mail header could lead to a one byte read past the end of a buffer. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

CVSS Details

CVSS 3.1 Base Score: 7.5
CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N)

Covered by Rapid7

Product	Vendor Advisory	Solution File	Added	Published
Alma_linux	—	Upgrade thunderbird	Oct 11, 2026	Sep 23, 2026
Debian	—	Upgrade thunderbird	Sep 21, 2026	Sep 1, 2026
Mozilla Thunderbird	—	Upgrade to the latest version of Mozilla ThunderbirdUpgrade to Mozilla Thunderbird version 153.2	Sep 1, 2026	Sep 1, 2026
Redhat_linux	—	Upgrade thunderbird-debuginfoUpgrade thunderbirdNo solution existsUpgrade thunderbird-debugsource	Sep 18, 2026	Sep 1, 2026
Rocky_linux	—	Upgrade thunderbird-debugsourceUpgrade thunderbirdUpgrade thunderbird-debuginfo	Sep 28, 2026	Sep 25, 2026

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CVSS Details

Covered by Rapid7

Prioritise with Active Threat Intelligence