# CVE-2026-42008: Auth bypass in OX Dovecot CE

> A trusted proxy can inject authentication fields to bypass password checks and log in as any user in Dovecot deployments with specific password database configurations.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** AZL-98325, DEBIAN-CVE-2026-42008, GHSA-hwmp-h522-jmhg, UBUNTU-CVE-2026-42008

## What is CVE-2026-42008?

CVE-2026-42008 is a medium-severity authentication bypass vulnerability in Open-Xchange GmbH OX Dovecot CE, published on 28 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Forwarding information received from a host listed as a trusted proxy is not kept separate from Dovecot's own authentication fields, so a value sent by that host can be injected as an internal authentication field. Any host permitted to act as a trusted proxy can authenticate as any user without knowing that user's password. This affects deployments whose password database honours a field that permits authentication without a password. Deployments that do not configure trusted proxies are not affected. Restrict the list of trusted proxy networks to hosts that are fully under your control. Update to non-vulnerable version. No publicly available exploits are known.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-42008?


## How do I fix CVE-2026-42008?

Upgrade to a fixed version.

## Is CVE-2026-42008 being exploited?

There is no known exploitation of CVE-2026-42008 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-42008 and fix it if it is affected.

What it is: CVE-2026-42008 is a medium-severity authentication bypass vulnerability in Open-Xchange GmbH OX Dovecot CE, published on 28 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-42008 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-2026-42008/ (Markdown: https://insights.sbomify.com/CVE-2026-42008/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-42008
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-42008
- OSV: https://osv.dev/vulnerability/CVE-2026-42008

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-42008/
Summaries are generated and may contain mistakes; the official description above is the record.