# CVE-2024-23185: Denial of service in OX Dovecot Pro

> Attackers can cause resource exhaustion via large headers, though MTA limits usually prevent remote DoS; self-DoS via APPEND is possible.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Sep 2024
- **Updated:** 4 Nov 2025
- **Also known as:** ALPINE-CVE-2024-23185, AZL-48984, AZL-49027, CLSA-2025-1753987188, DEBIAN-CVE-2024-23185, GHSA-g9m4-c8qf-67qw, UBUNTU-CVE-2024-23185

## What is CVE-2024-23185?

CVE-2024-23185 is a high-severity denial of service vulnerability in Open-Xchange GmbH OX Dovecot Pro, published on 10 Sep 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Very large headers can cause resource exhaustion when parsing message. The message-parser normally reads reasonably sized chunks of the message. However, when it feeds them to message-header-parser, it starts building up "full_value" buffer out of the smaller chunks. The full_value buffer has no size limit, so large headers can cause large memory usage. It doesn't matter whether it's a single long header line, or a single header split into multiple lines. This bug exists in all Dovecot versions. Incoming mails typically have some size limits set by MTA, so even largest possible header size may still fit into Dovecot's vsz_limit. So attackers probably can't DoS a victim user this way. A user could APPEND larger mails though, allowing them to DoS themselves (although maybe cause some memory issues for the backend in general). One can implement restrictions on headers on MTA component preceding Dovecot. No publicly available exploits are known.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2024-23185?


## How do I fix CVE-2024-23185?

Change a configuration setting.

## Is CVE-2024-23185 being exploited?

There is no known exploitation of CVE-2024-23185 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-23185 and fix it if it is affected.

What it is: CVE-2024-23185 is a high-severity denial of service vulnerability in Open-Xchange GmbH OX Dovecot Pro, published on 10 Sep 2024. 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-2024-23185 in the wild and no public exploit code.

Affected product: Open-Xchange GmbH OX Dovecot Pro. 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-2024-23185/ (Markdown: https://insights.sbomify.com/CVE-2024-23185/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-23185
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-23185
- OSV: https://osv.dev/vulnerability/CVE-2024-23185

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From sbomify Insights: https://insights.sbomify.com/CVE-2024-23185/
Summaries are generated and may contain mistakes; the official description above is the record.