{"id":"CVE-2026-64524","state":"PUBLISHED","title":"drm/hyperv: validate resolution_count and fix WIN8 fallback","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/hyperv: validate resolution_count and fix WIN8 fallback\n\nA SYNTHVID_RESOLUTION_RESPONSE with resolution_count > 64 walks past\nthe supported_resolution[SYNTHVID_MAX_RESOLUTION_COUNT] array in the\nparse loop. Bound resolution_count against the array size, folded\ninto the existing zero-check.\n\nWhen the WIN10 resolution probe fails, the caller in\nhyperv_connect_vsp() left hv->screen_*_max / preferred_* unpopulated,\nwhich sets mode_config.max_width / max_height to 0 and makes\ndrm_internal_framebuffer_create() reject every userspace framebuffer\nwith -EINVAL. The pre-WIN10 branch had the same gap for\npreferred_width / preferred_height. Use a single post-probe fallback\nguarded by screen_width_max == 0 so both paths converge on the WIN8\ndefaults.","publishedAt":"2026-07-25T09:20:48.193Z","updatedAt":"2026-10-19T20:48:38.013Z","severity":{"score":7.7,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","status":"affected","lessThan":"96f7de3172d4aa878b7f87173b2b3507c350fcd6","versionType":"git"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","status":"affected","lessThan":"bc573752f3dac0d1ab8df7078c1851bc76717653","versionType":"git"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","status":"affected","lessThan":"1fb565b77b8f44afabb02de6310065f109d89e94","versionType":"git"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","status":"affected","lessThan":"a321c908f2eeea01539668eb270d074d9b88e490","versionType":"git"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","status":"affected","lessThan":"9c698b2c43c2667c34f5336bf46ad5786216ac2a","versionType":"git"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","status":"affected","lessThan":"8a114b25b5521eae451b13bce98ae978624962e5","versionType":"git"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","status":"affected","lessThan":"13d33b9ef67066c77c84273fac5a1d3fde3533d1","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/gpu/drm/hyperv/hyperv_drm_proto.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.14","versionType":"semver"},{"version":"5.15.210","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.176","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.143","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.93","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.35","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.12","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/hyperv/hyperv_drm_proto.c"]}],"references":["https://git.kernel.org/stable/c/96f7de3172d4aa878b7f87173b2b3507c350fcd6","https://git.kernel.org/stable/c/bc573752f3dac0d1ab8df7078c1851bc76717653","https://git.kernel.org/stable/c/1fb565b77b8f44afabb02de6310065f109d89e94","https://git.kernel.org/stable/c/a321c908f2eeea01539668eb270d074d9b88e490","https://git.kernel.org/stable/c/9c698b2c43c2667c34f5336bf46ad5786216ac2a","https://git.kernel.org/stable/c/8a114b25b5521eae451b13bce98ae978624962e5","https://git.kernel.org/stable/c/13d33b9ef67066c77c84273fac5a1d3fde3533d1"],"weaknesses":["CWE-122"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/64xxx/CVE-2026-64524.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64524","state":"PUBLISHED","datePublished":"2026-07-25T09:20:48.193Z","dateUpdated":"2026-10-19T20:48:38.013Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-19T15:36:31.794Z"},"containers":{"cna":{"title":"drm/hyperv: validate resolution_count and fix WIN8 fallback","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/hyperv: validate resolution_count and fix WIN8 fallback\n\nA SYNTHVID_RESOLUTION_RESPONSE with resolution_count > 64 walks past\nthe supported_resolution[SYNTHVID_MAX_RESOLUTION_COUNT] array in the\nparse loop. Bound resolution_count against the array size, folded\ninto the existing zero-check.\n\nWhen the WIN10 resolution probe fails, the caller in\nhyperv_connect_vsp() left hv->screen_*_max / preferred_* unpopulated,\nwhich sets mode_config.max_width / max_height to 0 and makes\ndrm_internal_framebuffer_create() reject every userspace framebuffer\nwith -EINVAL. The pre-WIN10 branch had the same gap for\npreferred_width / preferred_height. Use a single post-probe fallback\nguarded by screen_width_max == 0 so both paths converge on the WIN8\ndefaults."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","status":"affected","lessThan":"96f7de3172d4aa878b7f87173b2b3507c350fcd6","versionType":"git"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","status":"affected","lessThan":"bc573752f3dac0d1ab8df7078c1851bc76717653","versionType":"git"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","status":"affected","lessThan":"1fb565b77b8f44afabb02de6310065f109d89e94","versionType":"git"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","status":"affected","lessThan":"a321c908f2eeea01539668eb270d074d9b88e490","versionType":"git"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","status":"affected","lessThan":"9c698b2c43c2667c34f5336bf46ad5786216ac2a","versionType":"git"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","status":"affected","lessThan":"8a114b25b5521eae451b13bce98ae978624962e5","versionType":"git"},{"version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","status":"affected","lessThan":"13d33b9ef67066c77c84273fac5a1d3fde3533d1","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/gpu/drm/hyperv/hyperv_drm_proto.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.14","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.14","versionType":"semver"},{"version":"5.15.210","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.176","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.143","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.93","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.35","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.12","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/hyperv/hyperv_drm_proto.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/96f7de3172d4aa878b7f87173b2b3507c350fcd6"},{"url":"https://git.kernel.org/stable/c/bc573752f3dac0d1ab8df7078c1851bc76717653"},{"url":"https://git.kernel.org/stable/c/1fb565b77b8f44afabb02de6310065f109d89e94"},{"url":"https://git.kernel.org/stable/c/a321c908f2eeea01539668eb270d074d9b88e490"},{"url":"https://git.kernel.org/stable/c/9c698b2c43c2667c34f5336bf46ad5786216ac2a"},{"url":"https://git.kernel.org/stable/c/8a114b25b5521eae451b13bce98ae978624962e5"},{"url":"https://git.kernel.org/stable/c/13d33b9ef67066c77c84273fac5a1d3fde3533d1"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","baseScore":7.7,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The malicious resolution response must originate from the local Hyper-V synthetic-video backend over VMBus; it is not reachable through a network protocol or guest userspace ioctl.\nAC:L - The backend can deterministically trigger the flaw by returning a resolution_count from 65 through 255 during the normal WIN10+ probe or resume exchange, without a race or unpredictable condition.\nPR:N - The guest accepts the VMBus response without authentication, capability checks, or guest credentials; a malicious or compromised backend requires no privileges within the vulnerable guest.\nUI:N - The response is processed automatically during device probing or resume, without any victim action.\nS:U - The vulnerable parser and the affected DRM and kernel resources are within the same guest-kernel security authority; this does not produce a guest-to-host escape.\nC:H - A count of 255 causes 191 additional four-byte entries to be read beyond the declared array, substantially exceeding a small bounded disclosure and allowing out-of-bounds kernel data to influence observable display state.\nI:N - The invalid accesses are reads, and their results are written only to the intended resolution fields; no out-of-bounds write, use-after-free, or control-flow corruption was found.\nA:H - Bounds-instrumented hardened kernels can oops when index 64 is reached, while a failed or malformed resolution probe can leave zero maximum dimensions and make every userspace framebuffer creation fail."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:42:37.752Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"5.15.210"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.1.176"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.6.143"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.12.93"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"6.18.35"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"7.0.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-64524","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T15:41:39.558295Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-122","lang":"en","type":"CWE","description":"CWE-122 Heap-based Buffer Overflow"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:48:38.013Z"}}]}}}