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CVE-2026-64524 (GCVE-0-2026-64524)

Vulnerability from cvelistv5 – Published: 2026-07-25 09:20 – Updated: 2026-08-05 12:42
VLAI
Title
drm/hyperv: validate resolution_count and fix WIN8 fallback
Summary
In the Linux kernel, the following vulnerability has been resolved: drm/hyperv: validate resolution_count and fix WIN8 fallback A SYNTHVID_RESOLUTION_RESPONSE with resolution_count > 64 walks past the supported_resolution[SYNTHVID_MAX_RESOLUTION_COUNT] array in the parse loop. Bound resolution_count against the array size, folded into the existing zero-check. When the WIN10 resolution probe fails, the caller in hyperv_connect_vsp() left hv->screen_*_max / preferred_* unpopulated, which sets mode_config.max_width / max_height to 0 and makes drm_internal_framebuffer_create() reject every userspace framebuffer with -EINVAL. The pre-WIN10 branch had the same gap for preferred_width / preferred_height. Use a single post-probe fallback guarded by screen_width_max == 0 so both paths converge on the WIN8 defaults.
Severity
7.7 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 76c56a5affeba1e163b66b9d8cc192e6154466f0 , < 96f7de3172d4aa878b7f87173b2b3507c350fcd6 (git)
Affected: 76c56a5affeba1e163b66b9d8cc192e6154466f0 , < bc573752f3dac0d1ab8df7078c1851bc76717653 (git)
Affected: 76c56a5affeba1e163b66b9d8cc192e6154466f0 , < 1fb565b77b8f44afabb02de6310065f109d89e94 (git)
Affected: 76c56a5affeba1e163b66b9d8cc192e6154466f0 , < a321c908f2eeea01539668eb270d074d9b88e490 (git)
Affected: 76c56a5affeba1e163b66b9d8cc192e6154466f0 , < 9c698b2c43c2667c34f5336bf46ad5786216ac2a (git)
Affected: 76c56a5affeba1e163b66b9d8cc192e6154466f0 , < 8a114b25b5521eae451b13bce98ae978624962e5 (git)
Affected: 76c56a5affeba1e163b66b9d8cc192e6154466f0 , < 13d33b9ef67066c77c84273fac5a1d3fde3533d1 (git)
guessed Create a notification for this product.
Linux Linux Affected: 5.14
Unaffected: 0 , < 5.14 (semver)
Unaffected: 5.15.210 , ≤ 5.15.* (semver)
Unaffected: 6.1.176 , ≤ 6.1.* (semver)
Unaffected: 6.6.143 , ≤ 6.6.* (semver)
Unaffected: 6.12.93 , ≤ 6.12.* (semver)
Unaffected: 6.18.35 , ≤ 6.18.* (semver)
Unaffected: 7.0.12 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

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          "product": "Linux",
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          "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 \u003e 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-\u003escreen_*_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."
        }
      ],
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
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              "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."
            }
          ]
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      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:42:37.752Z",
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        "shortName": "Linux"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64524",
    "datePublished": "2026-07-25T09:20:48.193Z",
    "dateReserved": "2026-07-19T15:36:31.794Z",
    "dateUpdated": "2026-08-05T12:42:37.752Z",
    "state": "PUBLISHED"
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            "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 \u003e 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-\u003escreen_*_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."
          }
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                "baseScore": 7.7,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "NONE",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
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          }
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-05T14:15:27+00:00",
      "cve": "CVE-2026-64524",
      "id": "CVE-2026-64524",
      "initial_release_date": "2026-07-25T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "91",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: drm/hyperv: validate resolution_count and fix WIN8 fallback",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64524.json",
      "version": "3"
    }
  }
}



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