# KB5000853: March 2021 security update

KB5000853, released March 9, 2021, fixes 27 CVEs across 4 products. None of them is reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/fix/microsoft/kb5000853
- Platform: Microsoft
- Released: Mar 9, 2021
- Priority: Urgent (Closes CVE-2021-26877, exploitation more likely)
- CVEs: 27, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://support.microsoft.com/help/5000853

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [Windows 8.1 for 32-bit systems](https://patchblox.com/security/data/product/microsoft/windows-8.1-for-32-bit-systems.md) |  |  |
| [Windows 8.1 for x64-based systems](https://patchblox.com/security/data/product/microsoft/windows-8.1-for-x64-based-systems.md) |  |  |
| [Windows Server 2012 R2](https://patchblox.com/security/data/product/microsoft/windows-server-2012-r2.md) |  |  |
| [Windows Server 2012 R2 (Server Core installation)](https://patchblox.com/security/data/product/microsoft/windows-server-2012-r2-server-core-installation.md) |  |  |

## CVEs this fix closes

| CVE | Priority | Component | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [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-2021-26861](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-2021-26862](https://patchblox.com/security/data/cve/CVE-2021-26862.md) | High | Windows Installer | 7.0 | 0.0125 |  |
| [CVE-2021-26873](https://patchblox.com/security/data/cve/CVE-2021-26873.md) | High | Windows User Profile Service | 7.0 | 0.0115 |  |
| [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-2021-26878](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-2021-26872](https://patchblox.com/security/data/cve/CVE-2021-26872.md) | High | Windows Event Tracing | 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-2021-26886](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 |  |

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Data as of 2026-11-07T06:34:28Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo