# CVE-2026-68204: media: vivid: check for vb2_is_busy() when toggling caps

> A race condition in the Linux kernel vivid driver allows unexpected format changes during buffer setup, potentially causing system instability or crashes.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/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:** 10 Aug 2026
- **Updated:** 19 Aug 2026
- **Also known as:** BELL-CVE-2026-68204, DEBIAN-CVE-2026-68204, GHSA-5xgr-hpwf-wcm3, UBUNTU-CVE-2026-68204

## What is CVE-2026-68204?

CVE-2026-68204 is a high-severity vulnerability in Linux, published on 10 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:

media: vivid: check for vb2_is_busy() when toggling caps

The vivid_update_format_cap/out() functions must only be called if the
capture/output queue are not busy. But for the controls that select
the CROP/COMPOSE/SCALE capability that is not checked.

Only when streaming starts will they be set to 'grabbed' and it is
impossible to change the control, but between REQBUFS and STREAMON you
are still allowed to set these controls. Since vivid_update_format_cap/out
will change the format, this can cause unexpected results.

Besides adding these checks, also add a WARN_ON in
vivid_update_format_cap/out() if the queue is busy.

I'm 90% certain that this is the cause of this syzbot bug:

https://syzkaller.appspot.com/bug?extid=dac8f5eaa46837e97b89

But since we never have reproducers, it is hard to be certain. In any case,
these checks are needed regardless.

## Which versions are affected by CVE-2026-68204?


## How do I fix CVE-2026-68204?

Apply the vendor's patch.

## Is CVE-2026-68204 being exploited?

There is no known exploitation of CVE-2026-68204 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68204 and fix it if it is affected.

What it is: CVE-2026-68204 is a high-severity vulnerability in Linux, published on 10 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-2026-68204 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-2026-68204/ (Markdown: https://insights.sbomify.com/CVE-2026-68204/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68204
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68204
- OSV: https://osv.dev/vulnerability/CVE-2026-68204

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68204/
Summaries are generated and may contain mistakes; the official description above is the record.