# CVE-2017-8623: Windows Hyper-V Denial of Service Vulnerability

CVE-2017-8623 is fixed in 4 products on 1 platform, first by KB4034658, released August 8, 2017. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2017-8623
- Priority: Routine
- CVSS: 5.8 (Important)
- EPSS: 0.0652
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Vendor exploitability assessment: Exploitation Unlikely
- Published: Aug 8, 2017
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2017-8623

## Description

<p>A denial of service vulnerability exists when Microsoft Hyper-V Network Switch on a host server fails to properly validate input from a privileged user on a guest operating system. An attacker who successfully exploited the vulnerability could cause the host server to crash.</p> <p>To exploit the vulnerability, an attacker who already has a privileged account on a guest operating system, running as a virtual machine, could run a specially crafted application that causes a host machine to crash.</p> <p>The update addresses the vulnerability by modifying how virtual machines access the Hyper-V Network Switch.</p>

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Microsoft | Windows 10 Version 1607 for x64-based Systems | 14393.1593 | [KB4034658](https://patchblox.com/security/data/fix/microsoft/kb4034658.md) | Aug 8, 2017 |
| Microsoft | Windows 10 Version 1703 for x64-based Systems | 15063.540 | [KB4034674](https://patchblox.com/security/data/fix/microsoft/kb4034674.md) | Aug 8, 2017 |
| Microsoft | Windows Server 2016 | 14393.1593 | [KB4034658](https://patchblox.com/security/data/fix/microsoft/kb4034658.md) | Aug 8, 2017 |
| Microsoft | Windows Server 2016 (Server Core installation) | 14393.1593 | [KB4034658](https://patchblox.com/security/data/fix/microsoft/kb4034658.md) | Aug 8, 2017 |

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Data as of 2026-11-07T12:40:37Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo