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Response snapshot Oct 26, 2026, 23:07 UTC

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VulnerabilityCVE-2026-63855

Linux kernel: drm/amdgpu/vcn: set no_user_fence for VCN v2.5 enc/dec rings

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu/vcn: set no_user_fence for VCN v2.5 enc/dec rings VCN encoder and decoder rings do not support 64-bit user fence writes, reject CS submissions with user fences.

At a glance

Exploited
Not known
Severity
7.8 High (CVSS 3.1)
Chance of exploitation
0.2% in the next 30 days
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-63855 (opens a new tab)

What happened

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

drm/amdgpu/vcn: set no_user_fence for VCN v2.5 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 efc9dd5590894109bce9a0bfe1fa5592dd6b20b1)

Scores and how they were measured

CVSS base severity

7.8

Version 3.1As of

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

0.2%

Scored Percentile 7.0%

Model and measurement source (opens a new tab)

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    NVD CVE-2026-63855 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  4. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  5. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-63855, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 26). Linux kernel: drm/amdgpu/vcn: set no_user_fence for VCN v2.5 enc/dec rings (CVE-2026-63855). https://kevwire.com/record/CVE-2026-63855

MLA

"Linux kernel: drm/amdgpu/vcn: set no_user_fence for VCN v2.5 enc/dec rings (CVE-2026-63855)." KEVWire, 26 Oct. 2026, kevwire.com/record/CVE-2026-63855.

Chicago

KEVWire. "Linux kernel: drm/amdgpu/vcn: set no_user_fence for VCN v2.5 enc/dec rings (CVE-2026-63855)." Last modified October 26, 2026. https://kevwire.com/record/CVE-2026-63855.

Evidence summary (plain text)

Linux kernel: drm/amdgpu/vcn: set no_user_fence for VCN v2.5 enc/dec rings (Jul 19, 2026).
In the Linux kernel, the following vulnerability has been resolved:

drm/amdgpu/vcn: set no_user_fence for VCN v2.5 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 efc9dd5590894109bce9a0bfe1fa5592dd6b20b1)
CVSS 7.8 (version 3.1; evidence as of Oct 26, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-63855).
EPSS 0.2% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-63855&date=2026-10-26).
Sources:
NVD CVE-2026-63855: https://nvd.nist.gov/vuln/detail/CVE-2026-63855
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T19:01:15.495Z&lastModEndDate=2026-10-26T20:30:55.133Z&resultsPerPage=500&startIndex=500
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T18:27:03.991Z&lastModEndDate=2026-10-26T20:00:55.952Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T17:56:10.576Z&lastModEndDate=2026-10-26T19:25:57.867Z&resultsPerPage=500&startIndex=500
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-63855&date=2026-10-26
Record ID: CVE-2026-63855.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 26, 2026, 19:40 UTC. Ingestion is not an independent editorial investigation.

NVD status: Analyzed. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

Record JSON

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Record details

Record detail