CVE-2026-118177
Calendar discovery accepted local file and remote network share locations
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.
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 / 9.1 critical |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H | ADP: CISA-ADP |
| 3.1 / 9.1 critical |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H | 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=2080924CNA: 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=2080924[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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