# CVE-2026-23555: Xenstored DoS by unprivileged domain

> An unprivileged guest can crash the Xenstore daemon or cause high CPU usage by accessing an illegal node path, impacting service availability.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 23 Mar 2026
- **Updated:** 23 Mar 2026
- **Also known as:** ALPINE-CVE-2026-23555, DEBIAN-CVE-2026-23555, GHSA-hv7f-mhvh-6mf6, UBUNTU-CVE-2026-23555

## What is CVE-2026-23555?

CVE-2026-23555 is a high-severity denial of service vulnerability in Xen Xen, published on 23 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Any guest issuing a Xenstore command accessing a node using the
(illegal) node path "/local/domain/", will crash xenstored due to a
clobbered error indicator in xenstored when verifying the node path.

Note that the crash is forced via a failing assert() statement in
xenstored. In case xenstored is being built with NDEBUG #defined,
an unprivileged guest trying to access the node path "/local/domain/"
will result in it no longer being serviced by xenstored, other guests
(including dom0) will still be serviced, but xenstored will use up
all cpu time it can get.

Weakness: CWE-617 (Reachable Assertion)

## Which versions are affected by CVE-2026-23555?

It affects 1 product.


Products: Xen Xen.

## How do I fix CVE-2026-23555?

Apply the vendor's patch.

## Is CVE-2026-23555 being exploited?

There is no known exploitation of CVE-2026-23555 in the wild and no public exploit code.

## Other vulnerabilities in Xen Xen

- [CVE-2017-10912](https://insights.sbomify.com/CVE-2017-10912/): Privilege escalation in n/a (critical 10.0)
- [CVE-2017-10918](https://insights.sbomify.com/CVE-2017-10918/): Memory corruption in n/a (critical 10.0)
- [CVE-2017-10920](https://insights.sbomify.com/CVE-2017-10920/): Memory corruption in n/a (critical 10.0)
- [CVE-2017-10921](https://insights.sbomify.com/CVE-2017-10921/): Memory corruption in n/a (critical 10.0)
- [CVE-2025-27466](https://insights.sbomify.com/CVE-2025-27466/): Mutiple vulnerabilities in the Viridian interface (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23555 and fix it if it is affected.

What it is: CVE-2026-23555 is a high-severity denial of service vulnerability in Xen Xen, published on 23 Mar 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-2026-23555 in the wild and no public exploit code.

Affected product: Xen Xen. 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-2026-23555/ (Markdown: https://insights.sbomify.com/CVE-2026-23555/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23555
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23555
- OSV: https://osv.dev/vulnerability/CVE-2026-23555

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23555/
Summaries are generated and may contain mistakes; the official description above is the record.