CVE-2026-63853 (GCVE-0-2026-63853)
Vulnerability from cvelistv5
Published
2026-07-19 14:04
Modified
2026-08-05 12:36
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
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)
References
Impacted products
Vendor Product Version
Linux Linux Version: 8da1170a16e4d4b49fa07d1f75ad480847ff7eca
Version: 8da1170a16e4d4b49fa07d1f75ad480847ff7eca
Version: 8da1170a16e4d4b49fa07d1f75ad480847ff7eca
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/gpu/drm/amd/amdgpu/vcn_v4_0.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "1286b6872de0aee1feeeaa6dbac86369806de9a5",
              "status": "affected",
              "version": "8da1170a16e4d4b49fa07d1f75ad480847ff7eca",
              "versionType": "git"
            },
            {
              "lessThan": "6bdd2ed6458d35c368fbe9550a4d7f342abd3a92",
              "status": "affected",
              "version": "8da1170a16e4d4b49fa07d1f75ad480847ff7eca",
              "versionType": "git"
            },
            {
              "lessThan": "51f694221047c84fa185be98210eb2c354ffb8c6",
              "status": "affected",
              "version": "8da1170a16e4d4b49fa07d1f75ad480847ff7eca",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/gpu/drm/amd/amdgpu/vcn_v4_0.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.19"
            },
            {
              "lessThan": "5.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.33",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.33",
                  "versionStartIncluding": "5.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.10",
                  "versionStartIncluding": "5.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1",
                  "versionStartIncluding": "5.19",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/amdgpu/vcn: set no_user_fence for VCN v4.0 enc ring\n\nVCN encoder and decoder rings do not support 64-bit user fence writes,\nreject CS submissions with user fences.\n\n(cherry picked from commit fd852c048b46f9825e904a4f3f4538fe9d8827d9)"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - Exploitation requires submitting a crafted AMDGPU command stream through DRM_IOCTL_AMDGPU_CS on a local /dev/dri/renderD* device; there is no network, adjacent-radio, or physical-access path to the vulnerable VCN v4.0 unified encoder ring handling.\nAC:L - An attacker with render-node access can deterministically submit a CS containing an AMDGPU_CHUNK_ID_FENCE chunk targeting the VCN encoder ring; no race, special timing, or victim state beyond having a VCN 4.0-capable AMDGPU is required.\nPR:L - The path is reachable by any local user who can open the DRM render node (typically membership in the render/video group on desktops, workstations, and cloud GPU VMs); it does not require real root in the init namespace.\nUI:N - Triggering the bug is fully programmatic via ioctl-based CS submission and does not require any victim to open files, mount filesystems, or perform other interactive actions.\nS:U - Impact is confined to the AMDGPU/VCN driver and GPU resources of the submitting security context; it does not cross a VM, container, or IOMMU security boundary to affect a different authority.\nC:H - Without the no_user_fence guard, amdgpu_ib_commit emits a 64-bit user fence (AMDGPU_FENCE_FLAG_64BIT) on a ring whose emit_fence path only supports 32-bit fence writes, causing the VCN hardware to perform an unvalidated GPU DMA write that can corrupt adjacent GPU-mapped memory and be leveraged for information disclosure.\nI:H - The same rogue GPU-initiated fence write is a memory-corruption primitive that can modify GPU-accessible buffers (including shared dma-buf mappings) outside the intended 8-byte fence field, enabling integrity violations and potential further exploitation.\nA:H - Malformed fence/trap commands on the VCN unified encoder ring can hang or fault the VCN block and force GPU/driver reset, denying graphics and compute availability to all users of the device on shared workstations and servers."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:36:31.693Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/1286b6872de0aee1feeeaa6dbac86369806de9a5"
        },
        {
          "url": "https://git.kernel.org/stable/c/6bdd2ed6458d35c368fbe9550a4d7f342abd3a92"
        },
        {
          "url": "https://git.kernel.org/stable/c/51f694221047c84fa185be98210eb2c354ffb8c6"
        }
      ],
      "title": "drm/amdgpu/vcn: set no_user_fence for VCN v4.0 enc ring",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63853",
    "datePublished": "2026-07-19T14:04:43.885Z",
    "dateReserved": "2026-07-19T07:54:57.016Z",
    "dateUpdated": "2026-08-05T12:36:31.693Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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