CVE-2026-83991 Windows Cloud Files Mini Filter Driver Tampering Vulnerability

{
  "id": "70c677926ebebaa11ea2c3a98bed3b0a40dd4e96111c409a9338f2e9f3ce6885",
  "url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-83991",
  "method": "llm",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2026-83991 Windows Cloud Files Mini Filter Driver Tampering Vulnerability",
    "summary": "Missing authentication for a critical function in the Windows Cloud Files Mini Filter Driver allows an authorized attacker to perform local tampering.",
    "evidence": "Missing authentication for critical function in Windows Cloud Files Mini Filter Driver allows an authorized attacker to perform tampering locally.",
    "products": [
      {
        "name": {
          "value": "Windows Cloud Files Mini Filter Driver",
          "evidence": "Windows Cloud Files Mini Filter Driver"
        },
        "prerequisites": [
          {
            "value": "an authorized attacker",
            "evidence": "allows an authorized attacker to perform tampering locally"
          }
        ],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "fixed_cves": [],
    "related_cves": [
      {
        "value": "CVE-2026-83991",
        "evidence": "CVE-2026-83991 Windows Cloud Files Mini Filter Driver Tampering Vulnerability"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "official-microsoft-security-updates",
  "document_id": 26740,
  "published_at": "2026-09-08T14:00:00+00:00"
}