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Advisory severityMedium5.5Red Hat Linux

Medium [CVE-2026-63856] set no_user_fence for VCN v2.0 enc/dec rings

This medium-severity Red Hat Linux advisory covers CVE-2026-63856 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 9.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-63856 Source published Source updated

VulniPulse record published Record updated

CVE-2026-63856
Affected products & platforms
Red Hat LinuxLinux Kernel
Open source advisory

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Summary

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu/vcn: set no_user_fence for VCN v2.0 enc/dec rings VCN encoder and decoder rings do not support 64-bit user fence writes, reject CS submissions with user fences. (cherry picked from commit e2b5499fca55f1a32960a311bbb62e35891eaf73) A flaw was found in the Linux kernel's AMDGPU Video Core Next (VCN) 2.0 component.

An attacker could exploit this by submitting command sequences with 64-bit user fences, leading to the rejection of these submissions and a denial of service for affected applications.

This vulnerability is evaluated as Moderate severity because successful exploitation requires local user access with rights to interact with GPU device nodes, and the impact is confined to a denial of service without compromising system confidentiality or integrity.

Deployments without AMD graphics hardware or systems not utilizing Video Core Next 2.0 video processing capabilities are unaffected. In typical enterprise server environments where direct GPU rendering interfaces are not exposed to untrusted users, risk exposure is minimal.

Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-617.

Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 9. Will not fix / out of support: Red Hat Enterprise Linux 6.

Affected versions

No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.

Official advisory · medium-confidence parse· fetched 5 days ago·verify at source

Fixed versions

No fixed release is recorded yet. That does not prove no patch exists. Confirm against the vendor advisory.

Official advisory · medium-confidence parse· fetched 5 days ago·verify at source

Mitigation

The source record does not include mitigation steps. That does not mean no fix exists. Read the vendor advisory below for the authoritative guidance.

Official advisory · medium-confidence parse· fetched 5 days ago·verify at source

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