{"id":"CVE-2026-63855","state":"PUBLISHED","title":"drm/amdgpu/vcn: set no_user_fence for VCN v2.5 enc/dec rings","description":"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)","publishedAt":"2026-07-19T14:04:45.096Z","updatedAt":"2026-10-30T12:27:18.153Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"28c17d72072b7ce5cc13a527dcbfc045cc995e7d","status":"affected","lessThan":"8156e258025f2a22fcf7486c96848ac3cd3541dd","versionType":"git"},{"version":"28c17d72072b7ce5cc13a527dcbfc045cc995e7d","status":"affected","lessThan":"2c6fb056567efb49f8674108b86088a1cfaa86d0","versionType":"git"},{"version":"28c17d72072b7ce5cc13a527dcbfc045cc995e7d","status":"affected","lessThan":"8f0ea4524dc71c6c9ec97f2711f46e12f624140f","versionType":"git"},{"version":"28c17d72072b7ce5cc13a527dcbfc045cc995e7d","status":"affected","lessThan":"602d4c5872b25ddd4d82fb2025efb9a05b187bb3","versionType":"git"},{"version":"28c17d72072b7ce5cc13a527dcbfc045cc995e7d","status":"affected","lessThan":"5a3c6f76cab164a5d803084908d7050f649ab7f9","versionType":"git"},{"version":"28c17d72072b7ce5cc13a527dcbfc045cc995e7d","status":"affected","lessThan":"4f317863a3ab212a027d8c8c3cc3af4e3fb95704","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.4","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.4","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.141","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.91","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.33","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.10","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c"]}],"references":["https://git.kernel.org/stable/c/8156e258025f2a22fcf7486c96848ac3cd3541dd","https://git.kernel.org/stable/c/2c6fb056567efb49f8674108b86088a1cfaa86d0","https://git.kernel.org/stable/c/8f0ea4524dc71c6c9ec97f2711f46e12f624140f","https://git.kernel.org/stable/c/602d4c5872b25ddd4d82fb2025efb9a05b187bb3","https://git.kernel.org/stable/c/5a3c6f76cab164a5d803084908d7050f649ab7f9","https://git.kernel.org/stable/c/4f317863a3ab212a027d8c8c3cc3af4e3fb95704"],"weaknesses":["CWE-20"],"ingestedAt":"2026-10-30T12:46:06.359Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/63xxx/CVE-2026-63855.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63855","state":"PUBLISHED","datePublished":"2026-07-19T14:04:45.096Z","dateUpdated":"2026-10-30T12:27:18.153Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T07:54:57.016Z"},"containers":{"cna":{"title":"drm/amdgpu/vcn: set no_user_fence for VCN v2.5 enc/dec rings","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)"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"28c17d72072b7ce5cc13a527dcbfc045cc995e7d","status":"affected","lessThan":"8156e258025f2a22fcf7486c96848ac3cd3541dd","versionType":"git"},{"version":"28c17d72072b7ce5cc13a527dcbfc045cc995e7d","status":"affected","lessThan":"2c6fb056567efb49f8674108b86088a1cfaa86d0","versionType":"git"},{"version":"28c17d72072b7ce5cc13a527dcbfc045cc995e7d","status":"affected","lessThan":"8f0ea4524dc71c6c9ec97f2711f46e12f624140f","versionType":"git"},{"version":"28c17d72072b7ce5cc13a527dcbfc045cc995e7d","status":"affected","lessThan":"602d4c5872b25ddd4d82fb2025efb9a05b187bb3","versionType":"git"},{"version":"28c17d72072b7ce5cc13a527dcbfc045cc995e7d","status":"affected","lessThan":"5a3c6f76cab164a5d803084908d7050f649ab7f9","versionType":"git"},{"version":"28c17d72072b7ce5cc13a527dcbfc045cc995e7d","status":"affected","lessThan":"4f317863a3ab212a027d8c8c3cc3af4e3fb95704","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.4","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.4","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.141","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.91","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.33","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.10","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/gpu/drm/amd/amdgpu/vcn_v2_5.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/8156e258025f2a22fcf7486c96848ac3cd3541dd"},{"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"}],"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."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:27:18.153Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.4","versionEndExcluding":"6.1.191"},{"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"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-63855","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:32:22.667512Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-20","lang":"en","type":"CWE","description":"CWE-20 Improper Input Validation"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:07:51.946Z"}}]}}}