CVE-2026-118180
Matrix homeserver could redirect the chat session to a local file or network share
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.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| Thunderbird Mozilla |
≥ 153.6; ≤ 153.* (unaffected, rpm) ≥ 159; ≤ * (unaffected, rpm) |
CNA: mozilla |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 7.5 high |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N | ADP: CISA-ADP |
| 3.1 / 7.5 high |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N | NVD: 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2080939CNA: mozilla
- https://www.mozilla.org/security/advisories/mfsa2026-121/CNA: mozilla
- https://www.mozilla.org/security/advisories/mfsa2026-122/CNA: mozilla
- https://bugzilla.mozilla.org/show_bug.cgi?id=2080939[email protected]
- https://www.mozilla.org/security/advisories/mfsa2026-121/[email protected]
- https://www.mozilla.org/security/advisories/mfsa2026-122/[email protected]
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