# CVE-2026-80548: s390/vfio_ccw: Selectively expand io_mutex

> A race condition in the s390 vfio_ccw driver could lead to system instability or denial of service due to improper mutex handling.

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/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:** 26 Aug 2026
- **Updated:** 16 Oct 2026
- **Also known as:** BELL-CVE-2026-80548, DEBIAN-CVE-2026-80548, GHSA-ccx7-24wp-j32x, UBUNTU-CVE-2026-80548

## What is CVE-2026-80548?

CVE-2026-80548 is a high-severity 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: Selectively expand io_mutex

The io_mutex was defined to serialize the io_regions, but then has
also sort of been associated with the I/O themselves because of
the close relationship they share.

With the handful of races that are possible, the choices are either to:
 A) expand the scope of io_mutex to close these remaining windows, or
 B) reduce the scope of io_mutex to just io_region, and introduce a new
    lock mechanism for the remaining I/O resources

This patch implements A, since B brings with it a lot more interactions
that would need to be tracked and kept in a correct hierarchy. It also
takes advantage of the workqueue element for cp_free() that now gets
called out of fsm_notoper(), which could be invoked out of an interrupt
context and thus cannot acquire a mutex itself.

## Which versions are affected by CVE-2026-80548?


## How do I fix CVE-2026-80548?

Apply the vendor's patch.

## Is CVE-2026-80548 being exploited?

There is no known exploitation of CVE-2026-80548 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80548 and fix it if it is affected.

What it is: CVE-2026-80548 is a high-severity 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-2026-80548 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-2026-80548/ (Markdown: https://insights.sbomify.com/CVE-2026-80548/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80548
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80548
- OSV: https://osv.dev/vulnerability/CVE-2026-80548

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-80548/
Summaries are generated and may contain mistakes; the official description above is the record.