# KB5001916: May 2021 security update

KB5001916, released May 11, 2021, fixes 7 CVEs in Microsoft SharePoint Server 2019. None of them is reported as exploited. Patch Radar priority: Urgent. The product is no longer supported.

- Web page: https://patchblox.com/security/fix/microsoft/kb5001916
- Platform: Microsoft
- Released: May 11, 2021
- Priority: Urgent (Closes CVE-2021-28474, exploitation more likely)
- CVEs: 7, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://support.microsoft.com/help/5001916

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [Microsoft SharePoint Server 2019](https://patchblox.com/security/data/product/microsoft/microsoft-sharepoint-server-2019.md) |  |  |

## CVEs this fix closes

| CVE | Priority | Component | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2021-28474](https://patchblox.com/security/data/cve/CVE-2021-28474.md) | Urgent | Microsoft Office SharePoint | 8.8 | 0.5077 | More likely |
| [CVE-2021-31181](https://patchblox.com/security/data/cve/CVE-2021-31181.md) | Urgent | Microsoft Office SharePoint | 8.8 | 0.2901 | More likely |
| [CVE-2021-31172](https://patchblox.com/security/data/cve/CVE-2021-31172.md) | High | Microsoft Office SharePoint | 7.1 | 0.0181 |  |
| [CVE-2021-28478](https://patchblox.com/security/data/cve/CVE-2021-28478.md) | High | Microsoft Office SharePoint | 7.6 | 0.0157 |  |
| [CVE-2021-31173](https://patchblox.com/security/data/cve/CVE-2021-31173.md) | Routine | Microsoft Office SharePoint | 5.3 | 0.0208 |  |
| [CVE-2021-26418](https://patchblox.com/security/data/cve/CVE-2021-26418.md) | Routine | Microsoft Office SharePoint | 4.6 | 0.0124 |  |
| [CVE-2021-31171](https://patchblox.com/security/data/cve/CVE-2021-31171.md) | Routine | Microsoft Office SharePoint | 4.1 | 0.0065 |  |

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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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo