# KB5007409: November 2021 security update

KB5007409, released November 9, 2021, fixes 3 CVEs across 5 products. One of them is being exploited (CVE-2021-42321); 1 on CISA KEV. Patch Radar priority: Patch now. The product is no longer supported.

- Web page: https://patchblox.com/security/fix/microsoft/kb5007409
- Platform: Microsoft
- Released: Nov 9, 2021
- Priority: Patch now (Closes CVE-2021-42321, exploited (CISA KEV, ransomware))
- CVEs: 3, exploited: 1, on CISA KEV: 1
- Vendor advisory: https://support.microsoft.com/help/5007409

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [Microsoft Exchange Server 2013 Cumulative Update 23](https://patchblox.com/security/data/product/microsoft/microsoft-exchange-server-2013-cumulative-update-23.md) |  |  |
| [Microsoft Exchange Server 2016 Cumulative Update 21](https://patchblox.com/security/data/product/microsoft/microsoft-exchange-server-2016-cumulative-update-21.md) |  |  |
| [Microsoft Exchange Server 2016 Cumulative Update 22](https://patchblox.com/security/data/product/microsoft/microsoft-exchange-server-2016-cumulative-update-22.md) |  |  |
| [Microsoft Exchange Server 2019 Cumulative Update 10](https://patchblox.com/security/data/product/microsoft/microsoft-exchange-server-2019-cumulative-update-10.md) |  |  |
| [Microsoft Exchange Server 2019 Cumulative Update 11](https://patchblox.com/security/data/product/microsoft/microsoft-exchange-server-2019-cumulative-update-11.md) |  |  |

## CVEs this fix closes

| CVE | Priority | Component | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2021-42321](https://patchblox.com/security/data/cve/CVE-2021-42321.md) | Patch now | Microsoft Exchange Server | 8.8 | 0.9174 | CISA KEV, Ransomware |
| [CVE-2021-41349](https://patchblox.com/security/data/cve/CVE-2021-41349.md) | Routine | Microsoft Exchange Server | 6.5 | 0.9350 |  |
| [CVE-2021-42305](https://patchblox.com/security/data/cve/CVE-2021-42305.md) | Routine | Microsoft Exchange Server | 6.5 | 0.0787 |  |

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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo