{
  "fix": "KB5003435",
  "url": "https://patchblox.com/security/fix/microsoft/kb5003435",
  "summary": "KB5003435, released May 11, 2021, fixes 4 CVEs across 5 products. One of them is being exploited (CVE-2021-31207); 1 on CISA KEV. Patch Radar priority: Patch now. The product is no longer supported.",
  "platform": "microsoft",
  "type": "kb",
  "releaseKind": "Security",
  "title": "May 2021 security update",
  "released": "2021-05-11T12:00:00Z",
  "priority": "Patch now",
  "priorityTier": 1,
  "priorityReason": "Closes CVE-2021-31207, exploited (CISA KEV, ransomware)",
  "supported": false,
  "cveCount": 4,
  "exploitedCveCount": 1,
  "kevCveCount": 1,
  "ransomwareCveCount": 1,
  "maxEpss": 0.99782,
  "maxCvss": 7.8,
  "vendorAdvisory": "https://support.microsoft.com/help/5003435",
  "appliesTo": [
    {
      "product": "Microsoft Exchange Server 2013 Cumulative Update 23",
      "productUrl": "https://patchblox.com/security/product/microsoft/microsoft-exchange-server-2013-cumulative-update-23",
      "fixedVersion": "",
      "supported": false
    },
    {
      "product": "Microsoft Exchange Server 2016 Cumulative Update 19",
      "productUrl": "https://patchblox.com/security/product/microsoft/microsoft-exchange-server-2016-cumulative-update-19",
      "fixedVersion": "",
      "supported": false
    },
    {
      "product": "Microsoft Exchange Server 2016 Cumulative Update 20",
      "productUrl": "https://patchblox.com/security/product/microsoft/microsoft-exchange-server-2016-cumulative-update-20",
      "fixedVersion": "",
      "supported": false
    },
    {
      "product": "Microsoft Exchange Server 2019 Cumulative Update 8",
      "productUrl": "https://patchblox.com/security/product/microsoft/microsoft-exchange-server-2019-cumulative-update-8",
      "fixedVersion": "",
      "supported": false
    },
    {
      "product": "Microsoft Exchange Server 2019 Cumulative Update 9",
      "productUrl": "https://patchblox.com/security/product/microsoft/microsoft-exchange-server-2019-cumulative-update-9",
      "fixedVersion": "",
      "supported": false
    }
  ],
  "cves": [
    {
      "cveId": "CVE-2021-31207",
      "url": "https://patchblox.com/security/cve/CVE-2021-31207",
      "title": "Microsoft Exchange Server Security Feature Bypass Vulnerability",
      "component": "Microsoft Exchange Server",
      "impact": "Security Feature Bypass",
      "priority": "Patch now",
      "severity": "Moderate",
      "cvss": 6.6,
      "epss": 0.99782,
      "kev": true,
      "ransomware": true,
      "exploited": true,
      "disclosed": true
    },
    {
      "cveId": "CVE-2021-31198",
      "url": "https://patchblox.com/security/cve/CVE-2021-31198",
      "title": "Microsoft Exchange Server Remote Code Execution Vulnerability",
      "component": "Microsoft Exchange Server",
      "impact": "Remote Code Execution",
      "priority": "High",
      "severity": "Important",
      "cvss": 7.8,
      "epss": 0.04873,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-31195",
      "url": "https://patchblox.com/security/cve/CVE-2021-31195",
      "title": "Microsoft Exchange Server Remote Code Execution Vulnerability",
      "component": "Microsoft Exchange Server",
      "impact": "Remote Code Execution",
      "priority": "Routine",
      "severity": "Important",
      "cvss": 6.5,
      "epss": 0.73676,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    },
    {
      "cveId": "CVE-2021-31209",
      "url": "https://patchblox.com/security/cve/CVE-2021-31209",
      "title": "Microsoft Exchange Server Spoofing Vulnerability",
      "component": "Microsoft Exchange Server",
      "impact": "Spoofing",
      "priority": "Routine",
      "severity": "Important",
      "cvss": 6.5,
      "epss": 0.02627,
      "kev": false,
      "ransomware": false,
      "exploited": false,
      "disclosed": false
    }
  ],
  "dataAsOf": "2026-11-07T06:34:28Z"
}