# CVE-2021-26412: Microsoft Exchange Server Remote Code Execution Vulnerability

CVE-2021-26412 is fixed in 5 products on 1 platform, first by KB5000871, released March 10, 2021. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2021-26412
- Priority: Urgent
- CVSS: 9.1 (Critical)
- EPSS: 0.3376
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Vendor exploitability assessment: Exploitation Less Likely
- Published: Mar 2, 2021
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-26412

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Microsoft | Microsoft Exchange Server 2013 Cumulative Update 23 |  | [KB5000871](https://patchblox.com/security/data/fix/microsoft/kb5000871.md) | Mar 10, 2021 |
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 18 |  | [KB5000871](https://patchblox.com/security/data/fix/microsoft/kb5000871.md) | Mar 10, 2021 |
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 19 |  | [KB5000871](https://patchblox.com/security/data/fix/microsoft/kb5000871.md) | Mar 10, 2021 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 7 |  | [KB5000871](https://patchblox.com/security/data/fix/microsoft/kb5000871.md) | Mar 10, 2021 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 8 |  | [KB5000871](https://patchblox.com/security/data/fix/microsoft/kb5000871.md) | Mar 10, 2021 |

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Data as of 2026-11-08T13:06:02Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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