# CVE-2026-40204: Auth bypass in OX Dovecot CE

> An authentication bypass vulnerability in Open-Xchange Dovecot allows attackers to circumvent security controls.

- **Severity:** Low 3.1 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** AZL-98301, DEBIAN-CVE-2026-40204, GHSA-wxgx-37c3-39ph, UBUNTU-CVE-2026-40204

## What is CVE-2026-40204?

CVE-2026-40204 is a low-severity authentication bypass vulnerability in Open-Xchange GmbH OX Dovecot CE, published on 28 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

None None None No publicly available exploits are known.

Weakness: CWE-284 (Improper Access Control)

## Which versions are affected by CVE-2026-40204?


## How do I fix CVE-2026-40204?

Apply the vendor's patch.

## Is CVE-2026-40204 being exploited?

There is no known exploitation of CVE-2026-40204 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40204 and fix it if it is affected.

What it is: CVE-2026-40204 is a low-severity authentication bypass vulnerability in Open-Xchange GmbH OX Dovecot CE, published on 28 Aug 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-40204 in the wild and no public exploit code.

Affected product: Open-Xchange GmbH OX Dovecot CE. 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-2026-40204/ (Markdown: https://insights.sbomify.com/CVE-2026-40204/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40204
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40204
- OSV: https://osv.dev/vulnerability/CVE-2026-40204

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-40204/
Summaries are generated and may contain mistakes; the official description above is the record.