CVE-2026-118177
When looking for calendars in a directory on a server, during account setup or when adding a new…
- Risk score
- 68/100
- CVSS
- 9.1 v3.1
- Exploit chance (30 days)
- 0.5%
- Published
- 27 Oct 2026
Open in the live forecast Today's forecast
What to know
- What it is
- 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 subscrib…
- Affected
- See advisory
- Fix
- Apply the vendor's security update; see the linked advisory.
- Exploitation
- No known exploitation
Why it is Amber
- CVSS 9.1 critical
- Remotely exploitable without logging in
References
Original 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.
Last activity 27 Oct 2026. Patch Forecast updates every hour.