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CVE-2026-84637 Details

Description

Malicious calendar invitations could use file URI attachments to launch local or network-hosted executables on Windows, bypassing Thunderbird's normal executable attachment protections. With the new invitation display enabled, the attachment could also appear under a misleading filename. This vulnerability was fixed in Thunderbird 154 and Thunderbird 153.2.

Metrics

CVSS 3.x Severity and Vector Strings:

CNA: CISA-ADPCVSS-B:9.8 CRITICALVector:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

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URL	Source(s)	Tag(s)
https://bugzilla.mozilla.org/show_bug.cgi?id=2043878	[email protected]	Permissions Required
https://www.mozilla.org/security/advisories/mfsa2026-78/	[email protected]	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-88/	[email protected]	Vendor Advisory

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-434	Unrestricted Upload of File with Dangerous Type	CISA-ADP

Affected Products

Product	Versions
mozilla thunderbird	< 153.2.0 >= 154.0, < 155.0
CPE cpe:2.3:a:mozilla:thunderbird:::::::: Remediation No remediation found in references.

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]