CVE-2026-63856 (GCVE-0-2026-63856)
Vulnerability from cvelistv5 – Published: 2026-07-19 14:04 – Updated: 2026-08-05 12:36
VLAI
EPSS
VEX
Title
drm/amdgpu/vcn: set no_user_fence for VCN v2.0 enc/dec rings
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)
Severity
7.8 (High)
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
1b61de45dfaff00b627e47349a019658e39268b9 , < f264019be80de79f84f464846451445923bffea0
(git)
Affected: 1b61de45dfaff00b627e47349a019658e39268b9 , < 5e777bc4cbe928ac0fd95e368fee1540f2ce4db2 (git) Affected: 1b61de45dfaff00b627e47349a019658e39268b9 , < ac06ce5cac9e711281585d09d00c6efcd9b86396 (git) Affected: 1b61de45dfaff00b627e47349a019658e39268b9 , < c71aecae98e42dcf2baf462df50b3a2cf1a93fe4 (git) Affected: 1b61de45dfaff00b627e47349a019658e39268b9 , < 8d80b293b41fcb5e9396db93e788b0f4ebcbafb7 (git) |
guessed | |
| Linux | Linux |
Affected:
5.3
Unaffected: 0 , < 5.3 (semver) Unaffected: 6.6.141 , ≤ 6.6.* (semver) Unaffected: 6.12.91 , ≤ 6.12.* (semver) Unaffected: 6.18.33 , ≤ 6.18.* (semver) Unaffected: 7.0.10 , ≤ 7.0.* (semver) Unaffected: 7.1 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "f264019be80de79f84f464846451445923bffea0",
"status": "affected",
"version": "1b61de45dfaff00b627e47349a019658e39268b9",
"versionType": "git"
},
{
"lessThan": "5e777bc4cbe928ac0fd95e368fee1540f2ce4db2",
"status": "affected",
"version": "1b61de45dfaff00b627e47349a019658e39268b9",
"versionType": "git"
},
{
"lessThan": "ac06ce5cac9e711281585d09d00c6efcd9b86396",
"status": "affected",
"version": "1b61de45dfaff00b627e47349a019658e39268b9",
"versionType": "git"
},
{
"lessThan": "c71aecae98e42dcf2baf462df50b3a2cf1a93fe4",
"status": "affected",
"version": "1b61de45dfaff00b627e47349a019658e39268b9",
"versionType": "git"
},
{
"lessThan": "8d80b293b41fcb5e9396db93e788b0f4ebcbafb7",
"status": "affected",
"version": "1b61de45dfaff00b627e47349a019658e39268b9",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.3"
},
{
"lessThan": "5.3",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.141",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.91",
"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": "6.6.141",
"versionStartIncluding": "5.3",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.91",
"versionStartIncluding": "5.3",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.33",
"versionStartIncluding": "5.3",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.0.10",
"versionStartIncluding": "5.3",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1",
"versionStartIncluding": "5.3",
"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 v2.0 enc/dec rings\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 e2b5499fca55f1a32960a311bbb62e35891eaf73)"
}
],
"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_CS ioctl to a local DRM render node (/dev/dri/renderD*); the vulnerable VCN v2.0 path is not reachable over the network.\nAC:L - An attacker with render-node access can reliably submit a VCN DEC/ENC command stream with an AMDGPU_CHUNK_ID_FENCE user-fence chunk; no race or victim-specific timing is required beyond having a VCN 2.0-capable AMDGPU.\nPR:L - Any unprivileged local user who can open the DRM render node (typical render-group membership on Linux desktops, or any app granted GPU access on RDNA1 systems) can trigger the bug without root or capabilities.\nUI:N - No victim interaction is needed; the attacker directly crafts and submits the malicious command submission via the AMDGPU DRM ioctl interface.\nS:U - The misdirected GPU fence write is constrained to the attacker\u0027s own GPU virtual address space via per-process amdgpu_vm page tables; impact remains within the same kernel/OS security authority, not a VM-guest-to-host or IOMMU-boundary escape.\nC:H - The unsupported 64-bit user fence causes the VCN engine to perform a misdirected GPU memory write (40-bit address truncation on the decoder ring), which is memory corruption that can be leveraged to corrupt adjacent GPU buffers and disclose their prior contents when read back.\nI:H - The VCN hardware performs a GPU-initiated write of the fence sequence to a potentially mis-targeted GPU virtual address, providing a memory-corruption write primitive within the submitter\u0027s GPU mappings that could be chained for further exploitation.\nA:H - Submitting an unsupported user fence to VCN rings can hang the video engine or trigger a GPU fault/reset (amdgpu_gpu_reset), denying GPU service to all local consumers including the display stack."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-05T12:36:34.905Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/f264019be80de79f84f464846451445923bffea0"
},
{
"url": "https://git.kernel.org/stable/c/5e777bc4cbe928ac0fd95e368fee1540f2ce4db2"
},
{
"url": "https://git.kernel.org/stable/c/ac06ce5cac9e711281585d09d00c6efcd9b86396"
},
{
"url": "https://git.kernel.org/stable/c/c71aecae98e42dcf2baf462df50b3a2cf1a93fe4"
},
{
"url": "https://git.kernel.org/stable/c/8d80b293b41fcb5e9396db93e788b0f4ebcbafb7"
}
],
"title": "drm/amdgpu/vcn: set no_user_fence for VCN v2.0 enc/dec rings",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-63856",
"datePublished": "2026-07-19T14:04:45.716Z",
"dateReserved": "2026-07-19T07:54:57.016Z",
"dateUpdated": "2026-08-05T12:36:34.905Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-63856",
"date": "2026-10-01",
"epss": "0.00175",
"percentile": "0.06277"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "f264019be80de79f84f464846451445923bffea0",
"status": "affected",
"version": "1b61de45dfaff00b627e47349a019658e39268b9",
"versionType": "git"
},
{
"lessThan": "5e777bc4cbe928ac0fd95e368fee1540f2ce4db2",
"status": "affected",
"version": "1b61de45dfaff00b627e47349a019658e39268b9",
"versionType": "git"
},
{
"lessThan": "ac06ce5cac9e711281585d09d00c6efcd9b86396",
"status": "affected",
"version": "1b61de45dfaff00b627e47349a019658e39268b9",
"versionType": "git"
},
{
"lessThan": "c71aecae98e42dcf2baf462df50b3a2cf1a93fe4",
"status": "affected",
"version": "1b61de45dfaff00b627e47349a019658e39268b9",
"versionType": "git"
},
{
"lessThan": "8d80b293b41fcb5e9396db93e788b0f4ebcbafb7",
"status": "affected",
"version": "1b61de45dfaff00b627e47349a019658e39268b9",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.3"
},
{
"lessThan": "5.3",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.141",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.91",
"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"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/amdgpu/vcn: set no_user_fence for VCN v2.0 enc/dec rings\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 e2b5499fca55f1a32960a311bbb62e35891eaf73)"
}
],
"id": "CVE-2026-63856",
"lastModified": "2026-07-27T17:44:23.777",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-07-19T15:16:52.440",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/5e777bc4cbe928ac0fd95e368fee1540f2ce4db2"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/8d80b293b41fcb5e9396db93e788b0f4ebcbafb7"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/ac06ce5cac9e711281585d09d00c6efcd9b86396"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/c71aecae98e42dcf2baf462df50b3a2cf1a93fe4"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/f264019be80de79f84f464846451445923bffea0"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-07-31T18:48:11+00:00",
"cve": "CVE-2026-63856",
"id": "CVE-2026-63856",
"initial_release_date": "2026-07-19T00:00:00+00:00",
"product_status:known_affected": "198",
"product_status:known_not_affected": "76",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: drm/amdgpu/vcn: set no_user_fence for VCN v2.0 enc/dec rings",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63856.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2026-10-01T00:49:46Z",
"cve": "CVE-2026-63856",
"id": "CVE-2026-63856",
"initial_release_date": "2026-07-24T16:21:46Z",
"product_status:known_affected": "580",
"product_status:known_not_affected": "143",
"product_status:recommended": "250",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-63856",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-63856.json",
"version": "10"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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