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

drm/amdgpu/vcn: set no_user_fence for VCN v4.0 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 fd852c048b46f9825e904a4f3f4538fe9d8827d9)
Published: 2026-07-19
Score: 7.8 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

A Linux kernel defect in the AMDGPU Virtual Codec Engine (VCN) board limits the handling of 64‑bit user fence writes. The kernel incorrectly rejects command streams that include such fences for the VCN v4.0 encoder and decoder rings, causing the driver to fail to process the submission and potentially disabling GPU functionality. This results in a denial of service for GPU operations. The weakness is identified as CWE‑1287, an input validation flaw.

Affected Systems

All Linux kernel versions that ship the AMDGPU driver with support for the VCN v4.0 encoder and decoder rings are affected. The issue is confined to AMD GPU hardware GPU drivers or hardware are not impacted.

Risk and Exploitability

The CVSS score of 7.8 indicates a high severity. The EPSS score of <1% suggests that exploitation is currently unlikely. The vulnerability is not listed in the CISA KEV is local, where a user with access to the GPU device can submit the denial of service. No remote or privilege‑escapable exploitation is described in the available information.

Generated by OpenCVE AI on July 30, 2026 at 21:58 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Upgrade the Linux kernel to a version that includes the commit adding the no_user_fence handling for VCN v4.0 rings, or apply the specific patch to a custom kernel build.
  • If a kernel update is not immediately available, restrict VCN v4.0 usage by disabling the encoder/decoder rings through driver configuration or by enabling the no_user_fence setting if supported.
  • Monitor system logs for errors related to rejected command streams and ensure GPU services remain operational after any changes.

Generated by OpenCVE AI on July 30, 2026 at 21:58 UTC.

Tracking

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Advisories
Source ID Title
Ubuntu USN Ubuntu USN USN-8593-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8603-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-8618-1 Linux kernel vulnerabilities
History

Tue, 21 Jul 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-1287
References
Metrics threat_severity

None

 threat_severity

Low

Mon, 20 Jul 2026 14:45:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

Sun, 19 Jul 2026 14:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu/vcn: set no_user_fence for VCN v4.0 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 fd852c048b46f9825e904a4f3f4538fe9d8827d9)
Title drm/amdgpu/vcn: set no_user_fence for VCN v4.0 enc ring
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-08-05T12:36:31.693Z

Reserved: 2026-07-19T07:54:57.016Z

Link: CVE-2026-63853

cve-icon Vulnrichment

No data.

cve-icon NVD

No data.

cve-icon Redhat

Severity : Low

Publid Date: 2026-07-19T00:00:00Z

Links: CVE-2026-63853 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-07-30T22:00:06Z

Weaknesses
  • CWE-1287

    Improper Validation of Specified Type of Input