CVE-2026-118177 Calendar discovery accepted local file and remote network share locations
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-118177?
CVE-2026-118177 is a vulnerability in Mozilla Thunderbird, published on 27 Oct 2026.
Official 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.
Which versions are affected by CVE-2026-118177?
How do I fix CVE-2026-118177?
No fix has been published for CVE-2026-118177 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-118177 being exploited?
There is no known exploitation of CVE-2026-118177 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-118177, GHSA-7w88-6r56-g2q9, UBUNTU-CVE-2026-118177.