# KB4457045: September 2018 security update

KB4457045, released September 12, 2018, fixes 1 CVE across 4 products. None of them is reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/fix/microsoft/kb4457045
- Platform: Microsoft
- Released: Sep 12, 2018
- Priority: Urgent (Closes CVE-2018-8421, rated Critical)
- CVEs: 1, exploited: 0, on CISA KEV: 0
- Vendor advisory: https://support.microsoft.com/help/4457045

## Applies to

| Product | Release | Fixed in |
|---|---|---|
| [Microsoft .NET Framework 3.5 on Windows 8.1 for 32-bit systems](https://patchblox.com/security/data/product/microsoft/microsoft-.net-framework-3.5-on-windows-8.1-for-32-bit-systems.md) |  |  |
| [Microsoft .NET Framework 3.5 on Windows 8.1 for x64-based systems](https://patchblox.com/security/data/product/microsoft/microsoft-.net-framework-3.5-on-windows-8.1-for-x64-based-systems.md) |  |  |
| [Microsoft .NET Framework 3.5 on Windows Server 2012 R2](https://patchblox.com/security/data/product/microsoft/microsoft-.net-framework-3.5-on-windows-server-2012-r2.md) |  |  |
| [Microsoft .NET Framework 3.5 on Windows Server 2012 R2 (Server Core installation)](https://patchblox.com/security/data/product/microsoft/microsoft-.net-framework-3.5-on-windows-server-2012-r2-server-core-installation.md) |  |  |

## CVEs this fix closes

| CVE | Priority | Component | CVSS | EPSS | Exploitation |
|---|---|---|---:|---:|---|
| [CVE-2018-8421](https://patchblox.com/security/data/cve/CVE-2018-8421.md) | Urgent | .NET Framework | n/a | 0.2908 |  |

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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo