thunderbird: When looking for calendars in a directory on a server, during account setup or when adding a new network calendar, Th...
CVE-2026-118177 is fixed in thunderbird on 1 platform, first by DEBIAN-CVE-2026-118177, released October 31, 2026. It is not reported as exploited. Patch Radar priority: Urgent.
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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| thunderbird · Debian 12.15 (bookworm) | 1:153.6.0esr-1~deb12u2 | DEBIAN-CVE-2026-118177 | Oct 31, 2026 |
| thunderbird · Debian 13.5 (trixie) | 1:153.6.0esr-1~deb13u1 | DEBIAN-CVE-2026-118177 | Oct 31, 2026 |
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