# CVE-2026-80554: s390/vfio_ccw: Limit the number of channel program segments

> A missing limit on channel program segments in the Linux kernel s390 vfio-ccw driver allows attackers to cause a denial of service via recursive processing.

- **Severity:** Critical 9.3 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/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:** 26 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** AZL-97772, BELL-CVE-2026-80554, DEBIAN-CVE-2026-80554, GHSA-42gq-4mc2-p2hw, UBUNTU-CVE-2026-80554

## What is CVE-2026-80554?

CVE-2026-80554 is a critical denial of service vulnerability in Linux, published on 26 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

s390/vfio_ccw: Limit the number of channel program segments

The processing of channel programs, and the CCWs within them, is done
recursively. As such, there is an arbitrary (but not architectural)
limit to the number of CCWs that can exist in a single channel program.

The vfio-ccw logic breaks these channel programs into segments whenever
it encounters a Transfer-In-Channel (TIC) CCW, and the combined number
of segments count towards the global limit. Impose an equivalent limit
to the number of segments until such logic can be made non-recursive.

## Which versions are affected by CVE-2026-80554?


## How do I fix CVE-2026-80554?

Apply the vendor's patch.

## Is CVE-2026-80554 being exploited?

There is no known exploitation of CVE-2026-80554 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80554 and fix it if it is affected.

What it is: CVE-2026-80554 is a critical denial of service vulnerability in Linux, published on 26 Aug 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-2026-80554 in the wild and no public exploit code.

Affected product: Linux. 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-2026-80554/ (Markdown: https://insights.sbomify.com/CVE-2026-80554/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80554
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80554
- OSV: https://osv.dev/vulnerability/CVE-2026-80554

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80554/
Summaries are generated and may contain mistakes; the official description above is the record.