# KB5066738: October 2025 security update

KB5066738, released October 14, 2025, fixes 1 CVE across 8 products. None of them is reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/fix/microsoft/kb5066738
- Platform: Microsoft
- Released: Oct 14, 2025
- Priority: High (Closes CVE-2025-55248, high severity)
- CVEs: 1, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://support.microsoft.com/help/5066738

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 Version 1809 for 32-bit Systems](https://patchblox.com/security/data/product/microsoft/microsoft-.net-framework-3.5-and-4.7.2-on-windows-10-version-1809-for-32-bit-systems.md) |  |  |
| [Microsoft .NET Framework 3.5 AND 4.7.2 on Windows 10 Version 1809 for x64-based Systems](https://patchblox.com/security/data/product/microsoft/microsoft-.net-framework-3.5-and-4.7.2-on-windows-10-version-1809-for-x64-based-systems.md) |  |  |
| [Microsoft .NET Framework 3.5 AND 4.7.2 on Windows Server 2019](https://patchblox.com/security/data/product/microsoft/microsoft-.net-framework-3.5-and-4.7.2-on-windows-server-2019.md) |  |  |
| [Microsoft .NET Framework 3.5 AND 4.7.2 on Windows Server 2019 (Server Core installation)](https://patchblox.com/security/data/product/microsoft/microsoft-.net-framework-3.5-and-4.7.2-on-windows-server-2019-server-core-installation.md) |  |  |
| [Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 1809 for 32-bit Systems](https://patchblox.com/security/data/product/microsoft/microsoft-.net-framework-3.5-and-4.8-on-windows-10-version-1809-for-32-bit-systems.md) |  |  |
| [Microsoft .NET Framework 3.5 AND 4.8 on Windows 10 Version 1809 for x64-based Systems](https://patchblox.com/security/data/product/microsoft/microsoft-.net-framework-3.5-and-4.8-on-windows-10-version-1809-for-x64-based-systems.md) |  |  |
| [Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2019](https://patchblox.com/security/data/product/microsoft/microsoft-.net-framework-3.5-and-4.8-on-windows-server-2019.md) |  |  |
| [Microsoft .NET Framework 3.5 AND 4.8 on Windows Server 2019 (Server Core installation)](https://patchblox.com/security/data/product/microsoft/microsoft-.net-framework-3.5-and-4.8-on-windows-server-2019-server-core-installation.md) |  |  |

## CVEs this fix closes

| CVE | Priority | Component | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2025-55248](https://patchblox.com/security/data/cve/CVE-2025-55248.md) | High | .NET, .NET Framework, Visual Studio | 8.5 | 0.0074 |  |

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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