{
  "cveId": "CVE-2021-31166",
  "url": "https://patchblox.com/security/cve/CVE-2021-31166",
  "summary": "CVE-2021-31166 is fixed in 7 products on 1 platform, first by KB5003173, released May 11, 2021. It is being exploited: CISA added it to the Known Exploited Vulnerabilities catalog on April 6, 2022. Patch Radar priority: Patch now.",
  "title": "HTTP Protocol Stack Remote Code Execution Vulnerability",
  "description": "",
  "published": "2021-05-11T12:00:00Z",
  "severity": "Critical",
  "cvss": 9.8,
  "epss": 0.99867,
  "epssPercentile": 0.99962,
  "priority": "Patch now",
  "priorityTier": 1,
  "exploited": true,
  "vendorExploited": false,
  "disclosed": false,
  "exploitabilityAssessment": "Exploitation More Likely",
  "kev": {
    "added": "2022-04-06T00:00:00Z",
    "due": "2022-04-27T00:00:00Z",
    "ransomware": false,
    "requiredAction": "Apply updates per vendor instructions."
  },
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-31166",
  "fixes": [
    {
      "platform": "microsoft",
      "product": "Windows 10 Version 2004 for 32-bit Systems",
      "fixedVersion": "",
      "fix": "KB5003173",
      "url": "https://patchblox.com/security/fix/microsoft/kb5003173",
      "released": "2021-05-11T00:00:00Z"
    },
    {
      "platform": "microsoft",
      "product": "Windows 10 Version 2004 for ARM64-based Systems",
      "fixedVersion": "",
      "fix": "KB5003173",
      "url": "https://patchblox.com/security/fix/microsoft/kb5003173",
      "released": "2021-05-11T00:00:00Z"
    },
    {
      "platform": "microsoft",
      "product": "Windows 10 Version 2004 for x64-based Systems",
      "fixedVersion": "",
      "fix": "KB5003173",
      "url": "https://patchblox.com/security/fix/microsoft/kb5003173",
      "released": "2021-05-11T00:00:00Z"
    },
    {
      "platform": "microsoft",
      "product": "Windows 10 Version 20H2 for 32-bit Systems",
      "fixedVersion": "",
      "fix": "KB5003173",
      "url": "https://patchblox.com/security/fix/microsoft/kb5003173",
      "released": "2021-05-11T00:00:00Z"
    },
    {
      "platform": "microsoft",
      "product": "Windows 10 Version 20H2 for ARM64-based Systems",
      "fixedVersion": "",
      "fix": "KB5003173",
      "url": "https://patchblox.com/security/fix/microsoft/kb5003173",
      "released": "2021-05-11T00:00:00Z"
    },
    {
      "platform": "microsoft",
      "product": "Windows Server, version 2004 (Server Core installation)",
      "fixedVersion": "",
      "fix": "KB5003173",
      "url": "https://patchblox.com/security/fix/microsoft/kb5003173",
      "released": "2021-05-11T00:00:00Z"
    },
    {
      "platform": "microsoft",
      "product": "Windows Server, version 20H2 (Server Core Installation)",
      "fixedVersion": "",
      "fix": "KB5003173",
      "url": "https://patchblox.com/security/fix/microsoft/kb5003173",
      "released": "2021-05-11T00:00:00Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T13:31:49Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}