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Fencer Intel
critical 9.8

CVE-2026-84637 json

Calendar invitation attachments could launch local executables

published 2mo ago modified 2mo ago also EUVD-2026-69703

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits
0
none known

Summary

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.

Patch / fix

  • mozilla thunderbird 153.2.0, 155.0
  • MozillaThunderbird SLE Workstation Extension 15 SP7, SLE Module for Package Hub 15 SP7 153.2.0-150400.13.3.1

suse advisories SUSE-SU-2026:4268-1

  • MozillaThunderbird openSUSE Tumbleweed 153.4.0-1.1

opensuse advisories openSUSE-SU-2026:12098-1

Is CVE-2026-84637 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-84637 updated cvss 8.8

thunderbird: Thunderbird: Arbitrary code execution via malicious calendar invitation attachments

  • Red Hat Enterprise Linux 8 thunderbird, thunderbird 140.14.0-1.el10_2 Red Hat Enterprise Linux 9 thunderbird, thunderbird 140.14.0-1.el10_2 Red Hat Enterprise Linux 10 thunderbird 140.14.0-1.el10_2
    not affected: component not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
2mo ago

Exploit prediction

0.63% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Mozilla Thunderbird

Classification

Weakness
  • CWE-434 Unrestricted Upload of File with Dangerous Type

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.