# CVE-2021-28451: Microsoft Excel Remote Code Execution Vulnerability

CVE-2021-28451 is fixed in 7 products on 1 platform, first by KB4504735, released April 13, 2021. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2021-28451
- Priority: High
- CVSS: 7.8 (Important)
- EPSS: 0.0250
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Vendor exploitability assessment: Exploitation Less Likely
- Published: Apr 13, 2021
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-28451

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Microsoft | Microsoft Excel 2013 RT Service Pack 1 |  | [KB4504735](https://patchblox.com/security/data/fix/microsoft/kb4504735.md) | Apr 13, 2021 |
| Microsoft | Microsoft Excel 2013 Service Pack 1 (32-bit editions) |  | [KB4504735](https://patchblox.com/security/data/fix/microsoft/kb4504735.md) | Apr 13, 2021 |
| Microsoft | Microsoft Excel 2013 Service Pack 1 (64-bit editions) |  | [KB4504735](https://patchblox.com/security/data/fix/microsoft/kb4504735.md) | Apr 13, 2021 |
| Microsoft | Microsoft Excel 2016 (32-bit edition) |  | [KB4504721](https://patchblox.com/security/data/fix/microsoft/kb4504721.md) | Apr 13, 2021 |
| Microsoft | Microsoft Excel 2016 (64-bit edition) |  | [KB4504721](https://patchblox.com/security/data/fix/microsoft/kb4504721.md) | Apr 13, 2021 |
| Microsoft | Microsoft Office Online Server |  | [KB4504714](https://patchblox.com/security/data/fix/microsoft/kb4504714.md) | Apr 13, 2021 |
| Microsoft | Microsoft Office Web Apps Server 2013 Service Pack 1 |  | [KB4504729](https://patchblox.com/security/data/fix/microsoft/kb4504729.md) | Apr 13, 2021 |

---

Data as of 2026-11-08T00:53:09Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.