# CVE-2026-33604: Other in OX Dovecot CE

> Attackers can bypass SMTP smuggling protections in Dovecot to inject spoofed emails into downstream servers via crafted message body line endings.

- **Severity:** Medium 5.9 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **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-2026-33604, AZL-98280, DEBIAN-CVE-2026-33604, GHSA-ccxf-782r-4742, UBUNTU-CVE-2026-33604

## What is CVE-2026-33604?

CVE-2026-33604 is a medium-severity vulnerability in Open-Xchange GmbH OX Dovecot CE, published on 28 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An attacker that can get Dovecot to relay a message, for example through Sieve redirect or submission relay, can use a crafted line ending in the message body to bypass the outbound protection that prevents message content from being interpreted as SMTP commands. A downstream mail server that hasn't yet fixed the SMTP smuggling vulnerability can be tricked into treating part of the message body as new SMTP commands, allowing injection of spoofed email. This is the same vulnerability class as CVE-2023-51764 and CVE-2023-51766. Where you control the receiving mail servers, ensure they reject bare carriage returns in message data. Update to non-vulnerable version. No publicly available exploits are known.

Weakness: CWE-655 (Insufficient Psychological Acceptability)

## Which versions are affected by CVE-2026-33604?


## How do I fix CVE-2026-33604?

Upgrade to a fixed version.

## Is CVE-2026-33604 being exploited?

There is no known exploitation of CVE-2026-33604 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33604 and fix it if it is affected.

What it is: CVE-2026-33604 is a medium-severity vulnerability in Open-Xchange GmbH OX Dovecot CE, published on 28 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-33604 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-2026-33604/ (Markdown: https://insights.sbomify.com/CVE-2026-33604/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33604
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33604
- OSV: https://osv.dev/vulnerability/CVE-2026-33604

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33604/
Summaries are generated and may contain mistakes; the official description above is the record.