# CVE-2026-27852: Denial of service in OX Dovecot CE

> An attacker can cause a denial of service by sending crafted emails that exhaust memory during IMAP parsing, affecting Dovecot users.

- **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:** 28 Aug 2026
- **Updated:** 28 Aug 2026
- **Also known as:** ALPINE-CVE-2026-27852, AZL-98289, DEBIAN-CVE-2026-27852, GHSA-8fwp-48xw-q2gf, UBUNTU-CVE-2026-27852

## What is CVE-2026-27852?

CVE-2026-27852 is a high-severity denial of service 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 send mail to a user can craft a message whose headers contain a very large number of email addresses or MIME parameters, which causes excessive memory usage when the message is later parsed. The message is still delivered, but reading it over IMAP can exhaust the memory limit of the process and terminate it, causing denial of service for the affected user. Update to non-vulnerable version. No publicly available exploits are known.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-27852?


## How do I fix CVE-2026-27852?

Upgrade to a fixed version.

## Is CVE-2026-27852 being exploited?

There is no known exploitation of CVE-2026-27852 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-27852 and fix it if it is affected.

What it is: CVE-2026-27852 is a high-severity denial of service 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-2026-27852 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-2026-27852/ (Markdown: https://insights.sbomify.com/CVE-2026-27852/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-27852
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-27852
- OSV: https://osv.dev/vulnerability/CVE-2026-27852

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-27852/
Summaries are generated and may contain mistakes; the official description above is the record.