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No exploitation reportedFix available

CVE-2026-118177

Calendar discovery accepted local file and remote network share locations

No exploitation reported by the sources we read.

  • Published2026-10-27
  • WeaknessCWE-601

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-10-2718:16CVE publishedCNA

Versions per branch

Products declared by the CNA1 product

As mozilla, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • Mozilla Thunderbird

    Not affected ≥ 153.6, ≤ 153.* · ≥ 159

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-10-27

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • MozillaThunderbirdopenSUSE:Tumbleweedall versions · fixed in 153.6.0-1.1
  • mozjs102Ubuntu:24.04:LTSall versions · no fixed version listedand 1 other package
  • mozjs38Ubuntu:18.04:LTSall versions · no fixed version listedand 1 other package
  • mozjs52Ubuntu:20.04:LTSall versions · no fixed version listedand 1 other package
  • mozjs78Ubuntu:22.04:LTSall versions · no fixed version listedand 3 other packages
  • thunderbirdDebian:14all versions · no fixed version listed
  • thunderbirdDebian:13all versions · fixed in 1:153.6.0esr-1~deb13u1
  • thunderbirdDebian:12all versions · fixed in 1:153.6.0esr-1~deb12u2

Vendor advisories

  • CVE-2026-118177 Red Hat Product Security10 known affected

    thunderbird: Calendar discovery accepted local file and remote network share locations

    thunderbird as a component of Red Hat Enterprise Linux 10 · thunderbird.src as a component of Red Hat Enterprise Linux 10 · thunderbird as a component of Red Hat Enterprise Linux 6 · +7 more

Full record on NVD

Fix

  1. Workaround from the vendor Red Hat Product Security CVE-2026-118177 · 10 products--- CME Mitigation Guidance (2026-11-03) --- Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to indepen…
  2. No fix available, says the vendor Red Hat Product Security CVE-2026-118177 · 6 productsFix deferred
  3. No fix planned, says the vendor Red Hat Product Security CVE-2026-118177 · 4 productsOut of support scope

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Published
2026-10-27
Last Modified
2026-11-04
NVD status
Deferred
GitHub Advisory
GHSA-7w88-6r56-g2q9

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.

Is CVE-2026-118177 actively exploited?

Active exploitation of CVE-2026-118177 has not been confirmed. Its EPSS score was 0.2% on 2026-11-04, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-118177?

CVE-2026-118177 has a CVSS v3 base score of 9.1 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H.

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