CVE-2026-84640

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 v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://bugzilla.mozilla.org/show_bug.cgi?id=2063964	Permissions 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

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:mozilla:thunderbird::::::::
	cpe:2.3:a:mozilla:thunderbird::::::::
	cpe:2.3:a:mozilla:thunderbird::::::::

History

No history.

Information

Published : 2026-09-01 22:17

Updated : 2026-09-03 19:01

NVD link : CVE-2026-84640

Mitre link : CVE-2026-84640

CVE.ORG link : CVE-2026-84640

JSON object : View

Products Affected

mozilla

thunderbird

CWE

CWE-126

Buffer Over-read

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