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CVE-2026-63940

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Ignore Port I/O requests of length '0' Explicitly ignore Port I/O requests of length '0' (or count '0'), so that setting up the software scratch area (and other code) doesn't have to worry about underflowing the length, and to allow for WARNing on trying to configure the scratch area with len==0.

Severity
CRITICAL
CVSS score
9.3 (v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-07-19 16:17:12.540000
Last modified
2026-10-30 13:19:22.840000
View original CVE JSON
{
  "id": "CVE-2026-63940",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-07-19T16:17:12.540",
  "lastModified": "2026-10-30T13:19:22.840",
  "vulnStatus": "Modified",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SEV: Ignore Port I/O requests of length '0'\n\nExplicitly ignore Port I/O requests of length '0' (or count '0'), so that\nsetting up the software scratch area (and other code) doesn't have to\nworry about underflowing the length, and to allow for WARNing on trying\nto configure the scratch area with len==0."
    }
  ],
  "affected": [
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      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "arch/x86/kvm/svm/sev.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
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          "vendor": "Linux",
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          "defaultStatus": "affected",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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            },
            {
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              "status": "unaffected"
            },
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              "lessThanOrEqual": "6.6.*",
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            },
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              "version": "6.12.95",
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              "status": "unaffected"
            },
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              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.0.12",
              "lessThanOrEqual": "7.0.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.1",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
          "baseScore": 9.3,
          "baseSeverity": "CRITICAL",
          "attackVector": "LOCAL",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "CHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 2.5,
        "impactScore": 6.0
      }
    ],
    "ssvcV203": [
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        "ssvcData": {
          "timestamp": "2026-10-16T15:33:50.957635Z",
          "id": "CVE-2026-63940",
          "options": [
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              "exploitation": "none"
            },
            {
              "automatable": "no"
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              "technicalImpact": "total"
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          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Primary",
      "description": [
        {
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          "value": "CWE-191"
        }
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  ],
  "configurations": [
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          "negate": false,
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      "url": "https://git.kernel.org/stable/c/2254972d4d69e279ba4e87bf0968eb08ad0d3c92",
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}