# KB5003611: July 2021 security update

KB5003611, released July 13, 2021, fixes 1 CVE in Microsoft Exchange Server 2016 Cumulative Update 21. None of them is reported as exploited. Patch Radar priority: High. The product is no longer supported.

- Web page: https://patchblox.com/security/fix/microsoft/kb5003611
- Platform: Microsoft
- Released: Jul 13, 2021
- Priority: High (Closes CVE-2021-34470, high severity)
- CVEs: 1, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://support.microsoft.com/help/5003611

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [Microsoft Exchange Server 2016 Cumulative Update 21](https://patchblox.com/security/data/product/microsoft/microsoft-exchange-server-2016-cumulative-update-21.md) |  |  |

## CVEs this fix closes

| CVE | Priority | Component | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2021-34470](https://patchblox.com/security/data/cve/CVE-2021-34470.md) | High | Microsoft Exchange Server | 8.0 | 0.0438 |  |

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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo