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Fencer Intel
critical 9.1

CVE-2026-118177 json

Calendar discovery accepted local file and remote network share locations

published 13d ago modified 5d ago also EUVD-2026-111354

cvss
9.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 39%
public exploits
0
none known

Summary

When looking for calendars in a directory on a server, during account setup or when adding a new network calendar, Thunderbird accepted calendar locations pointing to other servers, local files or network shares. A malicious server, or a network attacker when the lookup used plain HTTP, could make Thunderbird subscribe to such a location. On Windows this could leak the user's NTLM credentials to an attacker-controlled host on every calendar refresh, and changes to the calendar could be written to the attacker's share or overwrite a local file. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6.

Patch / fix

  • mozilla thunderbird 153.6, 159
  • mozilla thunderbird_esr 153.6, 159
  • thunderbird Debian 12 1:153.6.0esr-1~deb12u2
  • thunderbird Debian 13 1:153.6.0esr-1~deb13u1

debian advisories DEBIAN-CVE-2026-118177

  • MozillaThunderbird openSUSE Tumbleweed 153.6.0-1.1

opensuse advisories openSUSE-SU-2026:12339-1

Is CVE-2026-118177 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-2026-118177 updated cvss 7.5

thunderbird: Calendar discovery accepted local file and remote network share locations

  • Red Hat Enterprise Linux 6 thunderbird, thunderbird 140.17.0-1.el10_2 Red Hat Enterprise Linux 7 thunderbird, thunderbird 140.17.0-1.el10_2
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 thunderbird, thunderbird 140.17.0-1.el10_2 Red Hat Enterprise Linux 9 thunderbird, thunderbird 140.17.0-1.el10_2 Red Hat Enterprise Linux 10 rhel10/thunderbird-flatpak, thunderbird 140.17.0-1.el10_2
    affected: workaround, no fix available “Fix deferred”

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
partial
Assessed
5d ago

Exploit prediction

0.45% chance of exploitation in the next 30 days, higher than 39% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
CNA 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Affected products

  • Mozilla Thunderbird

Classification

Weakness
  • CWE-601 URL Redirection to Untrusted Site

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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.