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Fencer Intel
high 7.5

CVE-2026-118180 json

Matrix homeserver could redirect the chat session to a local file or network share

published 13d ago modified 5d ago also EUVD-2026-111357

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 25%
public exploits
0
none known

Summary

When logging in to a Matrix account, Thunderbird used the homeserver address provided in the server's login response without validating it. A malicious or compromised homeserver could provide a file: URL, causing Thunderbird to send all further Matrix requests of that session to local files or, on Windows, to an attacker-controlled network share, which could leak the user's NTLM credentials. The NTLM credential leak only affects Thunderbird on Windows. Other operating systems are unaffected. 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-2026-118180

  • MozillaThunderbird openSUSE Tumbleweed 153.6.0-1.1

opensuse advisories openSUSE-SU-2026:12339-1

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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-2026-118180 updated cvss 6.1

thunderbird: Matrix homeserver could redirect the chat session to a local file or network share

  • 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: 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: 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

0.32% chance of exploitation in the next 30 days, higher than 25% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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.