# CVE-2026-23039: drm/gud: fix NULL fb and crtc dereferences on USB disconnect

> A local attacker with physical access can cause a kernel crash by disconnecting a USB display, leading to denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 31 Jan 2026
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2026-23039, DEBIAN-CVE-2026-23039, GHSA-8v58-m3wh-hhg4, UBUNTU-CVE-2026-23039

## What is CVE-2026-23039?

CVE-2026-23039 is a vulnerability in Linux, published on 31 Jan 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

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

drm/gud: fix NULL fb and crtc dereferences on USB disconnect

On disconnect drm_atomic_helper_disable_all() is called which
sets both the fb and crtc for a plane to NULL before invoking a commit.

This causes a kernel oops on every display disconnect.

Add guards for those dereferences.

## Which versions are affected by CVE-2026-23039?


## How do I fix CVE-2026-23039?

Apply the vendor's patch.

## Is CVE-2026-23039 being exploited?

There is no known exploitation of CVE-2026-23039 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23039 and fix it if it is affected.

What it is: CVE-2026-23039 is a vulnerability in Linux, published on 31 Jan 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-23039 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-2026-23039/ (Markdown: https://insights.sbomify.com/CVE-2026-23039/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23039
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23039
- OSV: https://osv.dev/vulnerability/CVE-2026-23039

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23039/
Summaries are generated and may contain mistakes; the official description above is the record.