# CVE-2023-28366: Denial of service in n/a

> Remote attackers can cause a memory leak and denial of service in Eclipse Mosquitto by sending duplicate QoS 2 messages.

- **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:** 1 Sep 2023
- **Updated:** 26 Jun 2025
- **Also known as:** ALPINE-CVE-2023-28366, DEBIAN-CVE-2023-28366, GHSA-897v-899r-j3hg, MGASA-2025-0106, OESA-2023-1658, OESA-2023-1659, OESA-2023-1680, UBUNTU-CVE-2023-28366

## What is CVE-2023-28366?

CVE-2023-28366 is a high-severity denial of service vulnerability in n/a, published on 1 Sep 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The broker in Eclipse Mosquitto 1.3.2 through 2.x before 2.0.16 has a memory leak that can be abused remotely when a client sends many QoS 2 messages with duplicate message IDs, and fails to respond to PUBREC commands. This occurs because of mishandling of EAGAIN from the libc send function.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2023-28366?

It affects 1 product.


Products: Eclipse Mosquitto.

## How do I fix CVE-2023-28366?

Upgrade to a fixed version.

## Is CVE-2023-28366 being exploited?

There is no known exploitation of CVE-2023-28366 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2018-12550](https://insights.sbomify.com/CVE-2018-12550/): Auth bypass in Eclipse Mosquitto (high 8.1)
- [CVE-2018-12551](https://insights.sbomify.com/CVE-2018-12551/): Auth bypass in Eclipse Mosquitto (high 8.1)
- [CVE-2023-5632](https://insights.sbomify.com/CVE-2023-5632/): Unconditionally adding an event to the epoll causes excessive CPU consumption (high 7.5)
- [CVE-2021-41039](https://insights.sbomify.com/CVE-2021-41039/): Denial of service in Eclipse Mosquitto (high 7.5)
- [CVE-2021-34432](https://insights.sbomify.com/CVE-2021-34432/): Denial of service in Eclipse Mosquitto (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-28366 and fix it if it is affected.

What it is: CVE-2023-28366 is a high-severity denial of service vulnerability in n/a, published on 1 Sep 2023. 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-2023-28366 in the wild and no public exploit code.

Affected product: n/a. 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-2023-28366/ (Markdown: https://insights.sbomify.com/CVE-2023-28366/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-28366
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-28366
- OSV: https://osv.dev/vulnerability/CVE-2023-28366

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-28366/
Summaries are generated and may contain mistakes; the official description above is the record.