# CVE-2026-33607: Denial of service in OX Dovecot CE

> Authenticated attackers can cause CPU exhaustion and denial of service via the IMAP LIST command in Dovecot servers.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L`)
- **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:** ALPINE-CVE-2026-33607, AZL-98316, DEBIAN-CVE-2026-33607, GHSA-55w3-v95w-x9w3, UBUNTU-CVE-2026-33607

## What is CVE-2026-33607?

CVE-2026-33607 is a medium-severity denial of service 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

An attacker that has valid credentials can use IMAP LIST command to consume CPU. This can cause degradation or denial of service for IMAP. Monitor system for abnormal CPU usage and kill the offending process and lock account. Alternatively install fixed version. No publicly available exploits are known.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-33607?


## How do I fix CVE-2026-33607?

Upgrade to a fixed version.

## Is CVE-2026-33607 being exploited?

There is no known exploitation of CVE-2026-33607 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33607 and fix it if it is affected.

What it is: CVE-2026-33607 is a medium-severity denial of service 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-2026-33607 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-2026-33607/ (Markdown: https://insights.sbomify.com/CVE-2026-33607/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33607
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33607
- OSV: https://osv.dev/vulnerability/CVE-2026-33607

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33607/
Summaries are generated and may contain mistakes; the official description above is the record.