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CVE-2026-118177

UnknownEPSS 0.18%

Last modified

CVE-2026-118177 is a vulnerability of currently unknown severity. 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. EPSS estimates a 0.18% chance of exploitation in the next 30 days.

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.

Metrics

EPSS Probability
0.18%

7.5th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
MozillaThunderbirdAll versions

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2026-118177?
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.
How severe is CVE-2026-118177?
Severity scoring for CVE-2026-118177 is pending analysis. The EPSS model estimates a 0.18% probability of exploitation in the next 30 days.
How do I fix CVE-2026-118177?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST