What’s Vulnerable › Vulnerabilities

CVE-2020-16899: Windows TCP/IP Denial of Service Vulnerability

• Severity: high (CVSS 7.8 v2.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 13.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-10-16 · updated 2026-06-17

Description

<p>A denial of service vulnerability exists when the Windows TCP/IP stack improperly handles ICMPv6 Router Advertisement packets. An attacker who successfully exploited this vulnerability could cause a target system to stop responding.</p> <p>To exploit this vulnerability, an attacker would have to send specially crafted ICMPv6 Router Advertisement packets to a remote Windows computer. The vulnerability would not allow an attacker to execute code or to elevate user rights directly.</p> <p>The update addresses the vulnerability by correcting how the Windows TCP/IP stack handles ICMPv6 Router Advertisement packets.</p>

Affected products

• Microsoft Windows 10 Version 1607: 1709, 1803, 1809, 1903, 1909, 2004
• Microsoft Windows Server 2016: 1903, 1909, 2004
• Microsoft Windows Server 2019: all versions
• Microsoft Windows 10 1709: from 10.0.0 before publication — fixed in publication
• Microsoft Windows 10 Version 1709 for 32-bit Systems: from 10.0.0 before publication — fixed in publication
• Microsoft Windows 10 1803: from 10.0.0 before publication — fixed in publication
• Microsoft Windows 10: from 10.0.0 before publication — fixed in publication
• Microsoft Windows 10 Version 1903 for 32-bit Systems: from 10.0.0 before publication — fixed in publication
• Microsoft Windows 10 Version 1903 for ARM64-based Systems: from 10.0.0 before publication — fixed in publication
• Microsoft Windows 10 Version 1903 for x64-based Systems: from 10.0.0 before publication — fixed in publication
• Microsoft Windows 10 1909: from 10.0.0 before publication — fixed in publication
• Microsoft Windows 10 2004: from 10.0.0 before publication — fixed in publication
• Microsoft Windows Server 2019: from 10.0.0 before publication — fixed in publication
• Microsoft Windows Server, version 1903 (Server Core installation): from 10.0.0 before publication — fixed in publication
• Microsoft Windows Server, version 1909 (Server Core installation): from 10.0.0 before publication — fixed in publication
• Microsoft Windows Server version 2004: from 10.0.0 before publication — fixed in publication

How to fix

Upgrade to a fixed version: Microsoft Windows 10 1709 publication; Microsoft Windows 10 Version 1709 for 32-bit Systems publication; Microsoft Windows 10 1803 publication; Microsoft Windows 10 publication; Microsoft Windows 10 Version 1903 for 32-bit Systems publication; Microsoft Windows 10 Version 1903 for ARM64-based Systems publication; Microsoft Windows 10 Version 1903 for x64-based Systems publication; Microsoft Windows 10 1909 publication; Microsoft Windows 10 2004 publication; Microsoft Windows Server 2019 publication; Microsoft Windows Server, version 1903 (Server Core installation) publication; Microsoft Windows Server, version 1909 (Server Core installation) publication. Check the vendor advisory for mitigations.

References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-16899
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-16899

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