{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-63855", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.016Z", "datePublished": "2026-07-19T14:04:45.096Z", "dateUpdated": "2026-08-05T12:36:33.839Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:36:33.839Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/amdgpu/vcn: set no_user_fence for VCN v2.5 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 efc9dd5590894109bce9a0bfe1fa5592dd6b20b1)" } ], "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 - The vulnerability is reached only through the local DRM_AMDGPU_CS ioctl on a /dev/dri/renderD* node; there is no network, Bluetooth, or physical-access attack path to the VCN command submission code.\nAC:L - On affected AMD Instinct MI100 systems, an attacker with render-node access can reliably submit a VCN enc/dec command buffer with a user-fence chunk using standard libdrm/amdgpu APIs, triggering the malformed 64-bit fence write without races or victim-dependent timing.\nPR:L - Exploitation requires opening the DRM render node and submitting GPU commands, which needs only local user privileges (typically membership in the render/video group) on multi-tenant GPU cloud instances, workstations, or containers with GPU access—not root or capabilities obtainable only in the init namespace.\nUI:N - No victim interaction is required; the attacker directly crafts and submits the malicious command submission through the render node without needing another user to open files, mount filesystems, or perform any action.\nS:U - The misdirected GPU fence write corrupts memory within the attacker's own GPU virtual address space on the assigned device; it does not cross a VM, container, or IOMMU security boundary to affect another security authority.\nC:H - The bug causes GPU-initiated writes to an incorrectly decoded address, constituting out-of-bounds memory corruption that can be leveraged to read adjacent GPU-mapped buffers and disclose sensitive data from the attacker's or co-resident GPU allocations.\nI:H - The hardware fence completion write is an attacker-controlled 64-bit store to a mis-decoded GPU virtual address, providing an arbitrary GPU memory write primitive that could corrupt kernel-visible GTT mappings or GPU state for further exploitation.\nA:H - Misdirected fence writes to unmapped or invalid GPU addresses can cause GPU faults, engine hangs, or full GPU resets that deny video codec and compute service on the affected accelerator." } ] } ], "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_5.c" ], "versions": [ { "version": "28c17d72072b7ce5cc13a527dcbfc045cc995e7d", "lessThan": "2c6fb056567efb49f8674108b86088a1cfaa86d0", "status": "affected", "versionType": "git" }, { "version": "28c17d72072b7ce5cc13a527dcbfc045cc995e7d", "lessThan": "8f0ea4524dc71c6c9ec97f2711f46e12f624140f", "status": "affected", "versionType": "git" }, { "version": "28c17d72072b7ce5cc13a527dcbfc045cc995e7d", "lessThan": "602d4c5872b25ddd4d82fb2025efb9a05b187bb3", "status": "affected", "versionType": "git" }, { "version": "28c17d72072b7ce5cc13a527dcbfc045cc995e7d", "lessThan": "5a3c6f76cab164a5d803084908d7050f649ab7f9", "status": "affected", "versionType": "git" }, { "version": "28c17d72072b7ce5cc13a527dcbfc045cc995e7d", "lessThan": "4f317863a3ab212a027d8c8c3cc3af4e3fb95704", "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_5.c" ], "versions": [ { "version": "5.4", "status": "affected" }, { "version": "0", "lessThan": "5.4", "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": "5.4", "versionEndExcluding": "6.6.141" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4", "versionEndExcluding": "6.12.91" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4", "versionEndExcluding": "6.18.33" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4", "versionEndExcluding": "7.0.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4", "versionEndExcluding": "7.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/2c6fb056567efb49f8674108b86088a1cfaa86d0" }, { "url": "https://git.kernel.org/stable/c/8f0ea4524dc71c6c9ec97f2711f46e12f624140f" }, { "url": "https://git.kernel.org/stable/c/602d4c5872b25ddd4d82fb2025efb9a05b187bb3" }, { "url": "https://git.kernel.org/stable/c/5a3c6f76cab164a5d803084908d7050f649ab7f9" }, { "url": "https://git.kernel.org/stable/c/4f317863a3ab212a027d8c8c3cc3af4e3fb95704" } ], "title": "drm/amdgpu/vcn: set no_user_fence for VCN v2.5 enc/dec rings", "x_generator": { "engine": "bippy-1.2.0" } } } }