# CVE-2026-118180: Matrix homeserver could redirect the chat session to a local file or network share


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 27 Oct 2026
- **Updated:** 27 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-118180, GHSA-x88m-7whj-m9mh, UBUNTU-CVE-2026-118180

## What is CVE-2026-118180?

CVE-2026-118180 is a vulnerability in Mozilla Thunderbird, published on 27 Oct 2026. 

### Official description

When logging in to a Matrix account, Thunderbird used the homeserver address provided in the server's login response without validating it. A malicious or compromised homeserver could provide a file: URL, causing Thunderbird to send all further Matrix requests of that session to local files or, on Windows, to an attacker-controlled network share, which could leak the user's NTLM credentials.
The NTLM credential leak only affects Thunderbird on Windows. Other operating systems are unaffected. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6.

## Which versions are affected by CVE-2026-118180?


## How do I fix CVE-2026-118180?

No fix has been published for CVE-2026-118180 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-118180 being exploited?

There is no known exploitation of CVE-2026-118180 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-118180 and fix it if it is affected.

What it is: CVE-2026-118180 is a vulnerability in Mozilla Thunderbird, published on 27 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-118180 in the wild and no public exploit code.

Affected product: Mozilla Thunderbird. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-118180/ (Markdown: https://insights.sbomify.com/CVE-2026-118180/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-118180
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-118180
- OSV: https://osv.dev/vulnerability/CVE-2026-118180

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-118180/
Summaries are generated and may contain mistakes; the official description above is the record.