# KB5007012: October 2021 security update

KB5007012, released October 12, 2021, fixes 4 CVEs across 4 products. 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/kb5007012
- Platform: Microsoft
- Released: Oct 12, 2021
- Priority: High (Closes CVE-2021-34453, high severity)
- CVEs: 4, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://support.microsoft.com/help/5007012

## 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) |  |  |
| [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-2021-34453](https://patchblox.com/security/data/cve/CVE-2021-34453.md) | High | Microsoft Exchange Server | 7.5 | 0.0283 |  |
| [CVE-2021-26427](https://patchblox.com/security/data/cve/CVE-2021-26427.md) | High | Microsoft Exchange Server | 9.0 | 0.0089 |  |
| [CVE-2021-41348](https://patchblox.com/security/data/cve/CVE-2021-41348.md) | High | Microsoft Exchange Server | 8.0 | 0.0059 |  |
| [CVE-2021-41350](https://patchblox.com/security/data/cve/CVE-2021-41350.md) | Routine | Microsoft Exchange Server | 6.5 | 0.0191 |  |

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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo