# KB5001923: May 2021 security update

KB5001923, released May 11, 2021, fixes 4 CVEs across 2 products. None of them is reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/fix/microsoft/kb5001923
- Platform: Microsoft
- Released: May 11, 2021
- Priority: High (Closes CVE-2021-31179, high severity)
- CVEs: 4, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://support.microsoft.com/help/5001923

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [Microsoft Office 2016 (32-bit edition)](https://patchblox.com/security/data/product/microsoft/microsoft-office-2016-32-bit-edition.md) |  |  |
| [Microsoft Office 2016 (64-bit edition)](https://patchblox.com/security/data/product/microsoft/microsoft-office-2016-64-bit-edition.md) |  |  |

## CVEs this fix closes

| CVE | Priority | Component | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2021-31179](https://patchblox.com/security/data/cve/CVE-2021-31179.md) | High | Microsoft Office Excel | 7.8 | 0.1349 |  |
| [CVE-2021-31175](https://patchblox.com/security/data/cve/CVE-2021-31175.md) | High | Microsoft Office Excel | 7.8 | 0.0316 |  |
| [CVE-2021-31178](https://patchblox.com/security/data/cve/CVE-2021-31178.md) | Routine | Microsoft Office Excel | 5.5 | 0.1601 |  |
| [CVE-2021-31174](https://patchblox.com/security/data/cve/CVE-2021-31174.md) | Routine | Microsoft Office Excel | 5.5 | 0.0294 |  |

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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo