Vulnerability Description
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.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2080924
- https://www.mozilla.org/security/advisories/mfsa2026-121/
- https://www.mozilla.org/security/advisories/mfsa2026-122/
FAQ
What is CVE-2026-118177?
CVE-2026-118177 is a documented vulnerability. 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 net...
How severe is CVE-2026-118177?
CVSS scoring is not yet available for CVE-2026-118177. Check NVD for updates.
Is there a patch for CVE-2026-118177?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.