# KB5037037: April 2024 security update

KB5037037, released April 9, 2024, fixes 1 CVE 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/kb5037037
- Platform: Microsoft
- Released: Apr 9, 2024
- Priority: High (Closes CVE-2024-21409, high severity)
- CVEs: 1, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://support.microsoft.com/help/5037037

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [Microsoft .NET Framework 3.5 AND 4.8 on Windows 11 version 21H2 for ARM64-based Systems](https://patchblox.com/security/data/product/microsoft/microsoft-.net-framework-3.5-and-4.8-on-windows-11-version-21h2-for-arm64-based-systems.md) |  |  |
| [Microsoft .NET Framework 3.5 AND 4.8 on Windows 11 version 21H2 for x64-based Systems](https://patchblox.com/security/data/product/microsoft/microsoft-.net-framework-3.5-and-4.8-on-windows-11-version-21h2-for-x64-based-systems.md) |  |  |
| [Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 version 21H2 for ARM64-based Systems](https://patchblox.com/security/data/product/microsoft/microsoft-.net-framework-3.5-and-4.8.1-on-windows-11-version-21h2-for-arm64-based-systems.md) |  |  |
| [Microsoft .NET Framework 3.5 AND 4.8.1 on Windows 11 version 21H2 for x64-based Systems](https://patchblox.com/security/data/product/microsoft/microsoft-.net-framework-3.5-and-4.8.1-on-windows-11-version-21h2-for-x64-based-systems.md) |  |  |

## CVEs this fix closes

| CVE | Priority | Component | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2024-21409](https://patchblox.com/security/data/cve/CVE-2024-21409.md) | High | .NET and Visual Studio | 7.3 | 0.0251 |  |

---

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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo