# KB5000803: March 2021 cumulative update for Windows 10 1607 KB5000803, released March 9, 2021, fixes 36 CVEs across 10 products. One of them is being exploited (CVE-2021-26411); 1 on CISA KEV. Patch Radar priority: Patch now. - Web page: https://patchblox.com/security/fix/microsoft/kb5000803 - Platform: Microsoft - Released: Mar 9, 2021 - Priority: Patch now (Closes CVE-2021-26411, exploited (CISA KEV, ransomware)) - CVEs: 36, exploited: 1, on CISA KEV: 1 - Vendor advisory: https://support.microsoft.com/help/5000803 ## Applies to | Product | Release | Fixed in | |---|---|---| | [Internet Explorer 11 on Windows 10 Version 1607 for 32-bit Systems](https://patchblox.com/security/data/product/microsoft/internet-explorer-11-on-windows-10-version-1607-for-32-bit-systems.md) | | 14393.4283 | | [Internet Explorer 11 on Windows 10 Version 1607 for x64-based Systems](https://patchblox.com/security/data/product/microsoft/internet-explorer-11-on-windows-10-version-1607-for-x64-based-systems.md) | | 14393.4283 | | [Internet Explorer 11 on Windows Server 2016](https://patchblox.com/security/data/product/microsoft/internet-explorer-11-on-windows-server-2016.md) | | 14393.4283 | | [Microsoft Edge (EdgeHTML-based) on Windows 10 Version 1607 for 32-bit Systems](https://patchblox.com/security/data/product/microsoft/microsoft-edge-edgehtml-based-on-windows-10-version-1607-for-32-bit-systems.md) | | 14393.4283 | | [Microsoft Edge (EdgeHTML-based) on Windows 10 Version 1607 for x64-based Systems](https://patchblox.com/security/data/product/microsoft/microsoft-edge-edgehtml-based-on-windows-10-version-1607-for-x64-based-systems.md) | | 14393.4283 | | [Microsoft Edge (EdgeHTML-based) on Windows Server 2016](https://patchblox.com/security/data/product/microsoft/microsoft-edge-edgehtml-based-on-windows-server-2016.md) | | 14393.4283 | | [Windows 10 Version 1607 for 32-bit Systems](https://patchblox.com/security/data/product/microsoft/windows-10-version-1607-for-32-bit-systems.md) | | 14393.4283 | | [Windows 10 Version 1607 for x64-based Systems](https://patchblox.com/security/data/product/microsoft/windows-10-version-1607-for-x64-based-systems.md) | | 14393.4283 | | [Windows Server 2016](https://patchblox.com/security/data/product/microsoft/windows-server-2016.md) | | 14393.4283 | | [Windows Server 2016 (Server Core installation)](https://patchblox.com/security/data/product/microsoft/windows-server-2016-server-core-installation.md) | | 14393.4283 | ## CVEs this fix closes | CVE | Priority | Component | CVSS | EPSS | Exploitation | |---|---|---|---:|---:|---| | [CVE-2021-26411](https://patchblox.com/security/data/cve/CVE-2021-26411.md) | Patch now | Internet Explorer | 8.8 | 0.8167 | CISA KEV, Ransomware, Disclosed | | [CVE-2021-26877](https://patchblox.com/security/data/cve/CVE-2021-26877.md) | Urgent | Role: DNS Server | 9.8 | 0.1729 | More likely | | [CVE-2021-26897](https://patchblox.com/security/data/cve/CVE-2021-26897.md) | Urgent | Role: DNS Server | 9.8 | 0.1164 | More likely | | [CVE-2021-26868](https://patchblox.com/security/data/cve/CVE-2021-26868.md) | Urgent | Microsoft Graphics Component | 7.8 | 0.0308 | More likely | | [CVE-2021-26896](https://patchblox.com/security/data/cve/CVE-2021-26896.md) | High | Role: DNS Server | 7.5 | 0.0785 | | | [CVE-2021-26894](https://patchblox.com/security/data/cve/CVE-2021-26894.md) | High | Role: DNS Server | 9.8 | 0.0776 | | | [CVE-2021-26895](https://patchblox.com/security/data/cve/CVE-2021-26895.md) | High | Role: DNS Server | 9.8 | 0.0776 | | | [CVE-2021-26893](https://patchblox.com/security/data/cve/CVE-2021-26893.md) | High | Role: DNS Server | 9.8 | 0.0702 | | | [CVE-2021-27063](https://patchblox.com/security/data/cve/CVE-2021-27063.md) | High | Role: DNS Server | 7.5 | 0.0673 | | | [CVE-2021-26879](https://patchblox.com/security/data/cve/CVE-2021-26879.md) | High | Role: Windows Hyper-V | 7.5 | 0.0387 | | | [CVE-2021-26885](https://patchblox.com/security/data/cve/CVE-2021-26885.md) | High | Windows WalletService | 7.8 | 0.0349 | | | [CVE-2021-26861](https://patchblox.com/security/data/cve/CVE-2021-26861.md) | High | Microsoft Graphics Component | 7.8 | 0.0289 | | | [CVE-2021-26881](https://patchblox.com/security/data/cve/CVE-2021-26881.md) | High | Windows Media | 7.5 | 0.0283 | | | [CVE-2021-26882](https://patchblox.com/security/data/cve/CVE-2021-26882.md) | High | Windows Remote Access API | 7.8 | 0.0211 | | | [CVE-2021-27077](https://patchblox.com/security/data/cve/CVE-2021-27077.md) | High | Microsoft Graphics Component | 7.8 | 0.0144 | Disclosed | | [CVE-2021-26871](https://patchblox.com/security/data/cve/CVE-2021-26871.md) | High | Windows WalletService | 7.8 | 0.0143 | | | [CVE-2021-26862](https://patchblox.com/security/data/cve/CVE-2021-26862.md) | High | Windows Installer | 7.0 | 0.0125 | | | [CVE-2021-26866](https://patchblox.com/security/data/cve/CVE-2021-26866.md) | High | Windows Update Stack | 7.1 | 0.0116 | | | [CVE-2021-26873](https://patchblox.com/security/data/cve/CVE-2021-26873.md) | High | Windows User Profile Service | 7.0 | 0.0115 | | | [CVE-2021-26865](https://patchblox.com/security/data/cve/CVE-2021-26865.md) | High | Windows Container Execution Agent | 8.8 | 0.0108 | | | [CVE-2021-26899](https://patchblox.com/security/data/cve/CVE-2021-26899.md) | High | Windows UPnP Device Host | 7.8 | 0.0097 | | | [CVE-2021-1640](https://patchblox.com/security/data/cve/CVE-2021-1640.md) | High | Windows Print Spooler Components | 7.8 | 0.0095 | | | [CVE-2021-26898](https://patchblox.com/security/data/cve/CVE-2021-26898.md) | High | Windows Event Tracing | 7.8 | 0.0087 | | | [CVE-2021-26875](https://patchblox.com/security/data/cve/CVE-2021-26875.md) | High | Microsoft Graphics Component | 7.8 | 0.0087 | | | [CVE-2021-26891](https://patchblox.com/security/data/cve/CVE-2021-26891.md) | High | Windows Container Execution Agent | 7.8 | 0.0087 | | | [CVE-2021-26878](https://patchblox.com/security/data/cve/CVE-2021-26878.md) | High | Windows Print Spooler Components | 7.8 | 0.0085 | | | [CVE-2021-26901](https://patchblox.com/security/data/cve/CVE-2021-26901.md) | High | Windows Event Tracing | 7.8 | 0.0082 | | | [CVE-2021-26864](https://patchblox.com/security/data/cve/CVE-2021-26864.md) | High | Windows Registry | 8.4 | 0.0077 | | | [CVE-2021-26872](https://patchblox.com/security/data/cve/CVE-2021-26872.md) | High | Windows Event Tracing | 7.8 | 0.0075 | | | [CVE-2021-26880](https://patchblox.com/security/data/cve/CVE-2021-26880.md) | High | Windows Storage Spaces Controller | 7.8 | 0.0075 | | | [CVE-2020-16996](https://patchblox.com/security/data/cve/CVE-2020-16996.md) | Routine | Microsoft Windows | 6.5 | 0.0237 | | | [CVE-2021-26892](https://patchblox.com/security/data/cve/CVE-2021-26892.md) | Routine | Windows Extensible Firmware Interface | 6.2 | 0.0132 | | | [CVE-2021-26886](https://patchblox.com/security/data/cve/CVE-2021-26886.md) | Routine | Windows User Profile Service | 6.1 | 0.0113 | | | [CVE-2021-24107](https://patchblox.com/security/data/cve/CVE-2021-24107.md) | Routine | Windows Event Tracing | 5.5 | 0.0103 | | | [CVE-2021-26869](https://patchblox.com/security/data/cve/CVE-2021-26869.md) | Routine | Microsoft ActiveX | 5.5 | 0.0103 | | | [CVE-2021-26884](https://patchblox.com/security/data/cve/CVE-2021-26884.md) | Routine | Microsoft Windows Codecs Library | 5.5 | 0.0103 | | --- Data as of 2026-11-07T12:40:37Z UTC. 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