{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-63856", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.016Z", "datePublished": "2026-07-19T14:04:45.716Z", "dateUpdated": "2026-08-05T12:36:34.905Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:36:34.905Z" }, "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": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "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's 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's 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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c" ], "versions": [ { "version": "1b61de45dfaff00b627e47349a019658e39268b9", "lessThan": "f264019be80de79f84f464846451445923bffea0", "status": "affected", "versionType": "git" }, { "version": "1b61de45dfaff00b627e47349a019658e39268b9", "lessThan": "5e777bc4cbe928ac0fd95e368fee1540f2ce4db2", "status": "affected", "versionType": "git" }, { "version": "1b61de45dfaff00b627e47349a019658e39268b9", "lessThan": "ac06ce5cac9e711281585d09d00c6efcd9b86396", "status": "affected", "versionType": "git" }, { "version": "1b61de45dfaff00b627e47349a019658e39268b9", "lessThan": "c71aecae98e42dcf2baf462df50b3a2cf1a93fe4", "status": "affected", "versionType": "git" }, { "version": "1b61de45dfaff00b627e47349a019658e39268b9", "lessThan": "8d80b293b41fcb5e9396db93e788b0f4ebcbafb7", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c" ], "versions": [ { "version": "5.3", "status": "affected" }, { "version": "0", "lessThan": "5.3", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.141", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.91", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.33", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.10", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.6.141" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.12.91" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "6.18.33" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "7.0.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3", "versionEndExcluding": "7.1" } ] } ] } ], "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" } } } }