# CVE-2026-40223: Denial of service in systemd

> A local unprivileged user can cause a denial of service by triggering an assertion failure in systemd when specific unit configurations are active.

- **Severity:** Medium 4.7 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Apr 2026
- **Updated:** 15 Apr 2026
- **Also known as:** DEBIAN-CVE-2026-40223, GHSA-52rm-r39v-fwv9, GHSA-x4h8-rrrg-q78f

## What is CVE-2026-40223?

CVE-2026-40223 is a medium-severity denial of service vulnerability in Systemd Project Systemd, published on 10 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In systemd 258 before 260, a local unprivileged user can trigger an assert when a Delegate=yes and User=<unset> unit exists and is running.

Weakness: CWE-696 (Incorrect Behavior Order)

## Which versions are affected by CVE-2026-40223?

It affects 1 product.


Products: Systemd Project Systemd.

## How do I fix CVE-2026-40223?

Upgrade to a fixed version.

## Is CVE-2026-40223 being exploited?

There is no known exploitation of CVE-2026-40223 in the wild and no public exploit code.

## Other vulnerabilities in Systemd Project Systemd

- [CVE-2015-7510](https://insights.sbomify.com/CVE-2015-7510/): Memory corruption in n/a (critical 9.8)
- [CVE-2017-1000082](https://insights.sbomify.com/CVE-2017-1000082/): Privilege escalation in n/a (critical 9.8)
- [CVE-2016-10156](https://insights.sbomify.com/CVE-2016-10156/): Privilege escalation in n/a (high 7.8)
- [CVE-2017-9445](https://insights.sbomify.com/CVE-2017-9445/): Memory corruption in n/a (high 7.5)
- [CVE-2017-9217](https://insights.sbomify.com/CVE-2017-9217/): Null dereference in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40223 and fix it if it is affected.

What it is: CVE-2026-40223 is a medium-severity denial of service vulnerability in Systemd Project Systemd, published on 10 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-40223 in the wild and no public exploit code.

Affected product: Systemd Project Systemd. 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-2026-40223/ (Markdown: https://insights.sbomify.com/CVE-2026-40223/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40223
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40223
- OSV: https://osv.dev/vulnerability/CVE-2026-40223

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-40223/
Summaries are generated and may contain mistakes; the official description above is the record.