Public proof of conceptFix available

CVE-2020-16899

A public proof of concept exists; no exploitation attested.

Published2020-10-16

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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. 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. The update addresses the vulnerability by correcting how the Windows TCP/IP stack handles ICMPv6 Router Advertisement packets.

Timeline

dates in UTC

2020-10-1623:15CVE publishedNVD
2026-10-2319:23First public proof of conceptPoC-in-GitHub
2026-10-2319:23EPSS crossed 10 %FIRST EPSS

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-16899?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-16899?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Microsoft windows 10

Branch	Affected	Fixed in	Source
1709.x	= 1709	no fix published	NVD
1803.x	= 1803	no fix published	NVD
1809.x	= 1809	no fix published	NVD
1903.x	= 1903	no fix published	NVD
1909.x	= 1909	no fix published	NVD
2004.x	= 2004	no fix published	NVD

Microsoft windows server 2016

Branch	Affected	Fixed in	Source
1903.x	= 1903	no fix published	NVD
1909.x	= 1909	no fix published	NVD
2004.x	= 2004	no fix published	NVD

Microsoft windows server 2019

Branch	Affected	Fixed in	Source
—	all versions	no fix published	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Advisories and patches

portal.msrc.microsoft.comPatch · Vendor Advisory

Detection

read 2026-10-23 19:23 UTC

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: 1 repository, unverifiedadvanced-threat-research/CVE-2020-16899

Sources

CNACVSS 3.17.5read 2026-10-23
NVDCVSS 3.17.5read 2026-10-23
NVDCVSS 2.07.8read 2026-10-23
FIRST EPSSEPSS score13.5 %read 2026-10-23
PoC-in-GitHubproof of concept1read 2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published: 2020-10-16
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2020-16899?

Is CVE-2020-16899 actively exploited?

Active exploitation of CVE-2020-16899 has not been confirmed. Its EPSS score was 13.5% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-16899?

CVE-2020-16899 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Hear about the next vulnerability in your software

Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».

Get alerts for this product CISA KEV additions, October 2026 Search CVEs

No credit card required · No monthly cap on website lookups · 250 API requests/month

Go further

Following what attackers exploit right now? The CISA KEV additions of the month, with their patch deadlines.
Running this software? Vulnerability monitoring alerts you to new vulnerabilities in your products.

Related vulnerabilities

Same product first, then the same vendor advisory and the same publication week.

Back to CVE Database