{
  "fix": "KB5008255",
  "url": "https://patchblox.com/security/fix/microsoft/kb5008255",
  "summary": "KB5008255, released December 14, 2021, fixes 20 CVEs across 2 products. One of them is being exploited (CVE-2021-43226); 1 on CISA KEV. Patch Radar priority: Patch now.",
  "platform": "microsoft",
  "type": "kb",
  "releaseKind": "Security",
  "title": "December 2021 security update",
  "released": "2021-12-14T14:00:00Z",
  "priority": "Patch now",
  "priorityTier": 1,
  "priorityReason": "Closes CVE-2021-43226, exploited (CISA KEV, ransomware)",
  "supported": true,
  "cveCount": 20,
  "exploitedCveCount": 1,
  "kevCveCount": 1,
  "ransomwareCveCount": 1,
  "maxEpss": 0.12148,
  "maxCvss": 9.8,
  "vendorAdvisory": "https://support.microsoft.com/help/5008255",
  "appliesTo": [
    {
      "product": "Windows Server 2012",
      "productUrl": "https://patchblox.com/security/product/microsoft/windows-server-2012",
      "fixedVersion": "",
      "supported": true
    },
    {
      "product": "Windows Server 2012 (Server Core installation)",
      "productUrl": "https://patchblox.com/security/product/microsoft/windows-server-2012-server-core-installation",
      "fixedVersion": "",
      "supported": true
    }
  ],
  "cves": [
    {
      "cveId": "CVE-2021-43226",
      "url": "https://patchblox.com/security/cve/CVE-2021-43226",
      "title": "Windows Common Log File System Driver Elevation of Privilege Vulnerability",
      "component": "Windows Common Log File System Driver",
      "impact": "Elevation of Privilege",
      "priority": "Patch now",
      "severity": "Important",
      "cvss": 7.8,
      "epss": 0.03275,
      "kev": true,
      "ransomware": true,
      "exploited": true,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-43883",
      "url": "https://patchblox.com/security/cve/CVE-2021-43883",
      "title": "Windows Installer Elevation of Privilege Vulnerability",
      "component": "Windows Installer",
      "impact": "Elevation of Privilege",
      "priority": "Urgent",
      "severity": "Important",
      "cvss": 7.8,
      "epss": 0.12148,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": true
    },
    {
      "cveId": "CVE-2021-43217",
      "url": "https://patchblox.com/security/cve/CVE-2021-43217",
      "title": "Windows Encrypting File System (EFS) Remote Code Execution Vulnerability",
      "component": "Windows Encrypting File System (EFS)",
      "impact": "Remote Code Execution",
      "priority": "Urgent",
      "severity": "Critical",
      "cvss": 8.1,
      "epss": 0.0652,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-43215",
      "url": "https://patchblox.com/security/cve/CVE-2021-43215",
      "title": "iSNS Server Memory Corruption Vulnerability Can Lead to Remote Code Execution",
      "component": "Internet Storage Name Service",
      "impact": "Remote Code Execution",
      "priority": "Urgent",
      "severity": "Critical",
      "cvss": 9.8,
      "epss": 0.02867,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-43233",
      "url": "https://patchblox.com/security/cve/CVE-2021-43233",
      "title": "Remote Desktop Client Remote Code Execution Vulnerability",
      "component": "Remote Desktop Client",
      "impact": "Remote Code Execution",
      "priority": "Urgent",
      "severity": "Critical",
      "cvss": 7.5,
      "epss": 0.02363,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-41333",
      "url": "https://patchblox.com/security/cve/CVE-2021-41333",
      "title": "Windows Print Spooler Elevation of Privilege Vulnerability",
      "component": "Windows Print Spooler Components",
      "impact": "Elevation of Privilege",
      "priority": "Urgent",
      "severity": "Important",
      "cvss": 7.8,
      "epss": 0.01075,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": true
    },
    {
      "cveId": "CVE-2021-43207",
      "url": "https://patchblox.com/security/cve/CVE-2021-43207",
      "title": "Windows Common Log File System Driver Elevation of Privilege Vulnerability",
      "component": "Windows Common Log File System Driver",
      "impact": "Elevation of Privilege",
      "priority": "Urgent",
      "severity": "Important",
      "cvss": 7.8,
      "epss": 0.00679,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-43893",
      "url": "https://patchblox.com/security/cve/CVE-2021-43893",
      "title": "Windows Encrypting File System (EFS) Elevation of Privilege Vulnerability",
      "component": "Windows Encrypting File System (EFS)",
      "impact": "Elevation of Privilege",
      "priority": "High",
      "severity": "Important",
      "cvss": 7.5,
      "epss": 0.06719,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": true
    },
    {
      "cveId": "CVE-2021-43222",
      "url": "https://patchblox.com/security/cve/CVE-2021-43222",
      "title": "Microsoft Message Queuing Information Disclosure Vulnerability",
      "component": "Windows Message Queuing",
      "impact": "Information Disclosure",
      "priority": "High",
      "severity": "Important",
      "cvss": 7.5,
      "epss": 0.03167,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-43236",
      "url": "https://patchblox.com/security/cve/CVE-2021-43236",
      "title": "Microsoft Message Queuing Information Disclosure Vulnerability",
      "component": "Windows Message Queuing",
      "impact": "Information Disclosure",
      "priority": "High",
      "severity": "Important",
      "cvss": 7.5,
      "epss": 0.03167,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-43232",
      "url": "https://patchblox.com/security/cve/CVE-2021-43232",
      "title": "Windows Event Tracing Remote Code Execution Vulnerability",
      "component": "Windows Event Tracing",
      "impact": "Remote Code Execution",
      "priority": "High",
      "severity": "Important",
      "cvss": 7.8,
      "epss": 0.02181,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-43234",
      "url": "https://patchblox.com/security/cve/CVE-2021-43234",
      "title": "Windows Fax Service Remote Code Execution Vulnerability",
      "component": "Role: Windows Fax Service",
      "impact": "Remote Code Execution",
      "priority": "High",
      "severity": "Important",
      "cvss": 7.8,
      "epss": 0.02181,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-43229",
      "url": "https://patchblox.com/security/cve/CVE-2021-43229",
      "title": "Windows NTFS Elevation of Privilege Vulnerability",
      "component": "Windows NTFS",
      "impact": "Elevation of Privilege",
      "priority": "High",
      "severity": "Important",
      "cvss": 7.8,
      "epss": 0.01787,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-43238",
      "url": "https://patchblox.com/security/cve/CVE-2021-43238",
      "title": "Windows Remote Access Elevation of Privilege Vulnerability",
      "component": "Windows Remote Access Connection Manager",
      "impact": "Elevation of Privilege",
      "priority": "High",
      "severity": "Important",
      "cvss": 7.8,
      "epss": 0.00914,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-40441",
      "url": "https://patchblox.com/security/cve/CVE-2021-40441",
      "title": "Windows Media Center Elevation of Privilege Vulnerability",
      "component": "Windows Media",
      "impact": "Elevation of Privilege",
      "priority": "High",
      "severity": "Important",
      "cvss": 7.8,
      "epss": 0.00718,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-43230",
      "url": "https://patchblox.com/security/cve/CVE-2021-43230",
      "title": "Windows NTFS Elevation of Privilege Vulnerability",
      "component": "Windows NTFS",
      "impact": "Elevation of Privilege",
      "priority": "High",
      "severity": "Important",
      "cvss": 7.8,
      "epss": 0.00571,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-43223",
      "url": "https://patchblox.com/security/cve/CVE-2021-43223",
      "title": "Windows Remote Access Connection Manager Elevation of Privilege Vulnerability",
      "component": "Windows Remote Access Connection Manager",
      "impact": "Elevation of Privilege",
      "priority": "High",
      "severity": "Important",
      "cvss": 7.8,
      "epss": 0.00543,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-43248",
      "url": "https://patchblox.com/security/cve/CVE-2021-43248",
      "title": "Windows Digital Media Receiver Elevation of Privilege Vulnerability",
      "component": "Microsoft Windows Codecs Library",
      "impact": "Elevation of Privilege",
      "priority": "High",
      "severity": "Important",
      "cvss": 7.8,
      "epss": 0.00543,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-43224",
      "url": "https://patchblox.com/security/cve/CVE-2021-43224",
      "title": "Windows Common Log File System Driver Information Disclosure Vulnerability",
      "component": "Windows Common Log File System Driver",
      "impact": "Information Disclosure",
      "priority": "Routine",
      "severity": "Important",
      "cvss": 5.5,
      "epss": 0.03933,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-43216",
      "url": "https://patchblox.com/security/cve/CVE-2021-43216",
      "title": "Microsoft Local Security Authority (LSA) Server Information Disclosure Vulnerability",
      "component": "Microsoft Local Security Authority Server (lsasrv)",
      "impact": "Information Disclosure",
      "priority": "Routine",
      "severity": "Important",
      "cvss": 6.5,
      "epss": 0.0343,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    }
  ],
  "dataAsOf": "2026-11-07T06:34:28Z"
}