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CVE-2026-84640 Details
Description
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.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Sep 2, 2026Exploitation: NoneAutomatable: YesTechnical Impact: Partial
References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://bugzilla.mozilla.org/show_bug.cgi?id=2063964 | [email protected] | Permissions Required |
| https://www.mozilla.org/security/advisories/mfsa2026-86/ | [email protected] | Vendor Advisory |
| https://www.mozilla.org/security/advisories/mfsa2026-87/ | [email protected] | Vendor Advisory |
| https://www.mozilla.org/security/advisories/mfsa2026-88/ | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-126 | Buffer Over-read | CISA-ADP |
Affected Products
| Product | Versions |
|---|---|
| mozilla thunderbird | < 140.15.0 >= 141.0, < 153.2.0 >= 154.0, < 155.0 |
CPE
Remediation
| |
Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 3, 2026 | Initial Analysis | [email protected] |
| Sep 2, 2026 | CVE Modified | CISA-ADP |
| Sep 1, 2026 | New CVE Received | [email protected] |