# CVE-2026-63849: drm/amdgpu/vcn: set no_user_fence for VCN v5.0.1 enc ring

> A missing check in the AMD GPU VCN driver allows invalid user fence submissions, 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:** 19 Jul 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-63849, DEBIAN-CVE-2026-63849, GHSA-r2qg-mr7w-fwj6, UBUNTU-CVE-2026-63849

## What is CVE-2026-63849?

CVE-2026-63849 is a high-severity vulnerability in Linux kernel, published on 19 Jul 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:

drm/amdgpu/vcn: set no_user_fence for VCN v5.0.1 enc ring

VCN encoder and decoder rings do not support 64-bit user fence writes,
reject CS submissions with user fences.

(cherry picked from commit e16be95a2c3ee712b142cb27d2dca0b461181359)

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-63849?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-63849?

Apply the vendor's patch.

## Is CVE-2026-63849 being exploited?

There is no known exploitation of CVE-2026-63849 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63849 and fix it if it is affected.

What it is: CVE-2026-63849 is a high-severity vulnerability in Linux kernel, published on 19 Jul 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-2026-63849 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2026-63849/ (Markdown: https://insights.sbomify.com/CVE-2026-63849/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63849
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63849
- OSV: https://osv.dev/vulnerability/CVE-2026-63849

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63849/
Summaries are generated and may contain mistakes; the official description above is the record.