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CVE-2026-84637

Calendar invitation attachments could launch local executables

Published: Sep 1, 2026Updated: Sep 3, 2026 Sources: CVE List NVDCWE-434
9.8CRITICAL
NVD MITRE
EPSS Score
0.3%
Top 73.2%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:HI:HA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-434

Affected Products

Mozilla
oss-project·USaka mozilla corp.
ThunderbirdOn-premDesktop App
Communications / email-server-client
and 1 more affected products View all →

Exploitability

Official Patch Available
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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

3 techniques
Command and Control
Initial Access
Persistence
View detailed technique mapping

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2043878
bugzilla.mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-78/
mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-88/
mozilla.org

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