CVE-2021-31166 CRITICAL

CVE-2021-31166: HTTP Protocol Stack Remote Code Execution Vulnerability

Vendor Microsoft
Product Windows 10 Version 2004
KEV Status Known Exploited
Published May 11, 2021
Last update October 21, 2025
View on NVD All CVEs

CVSS base score

9.8/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

What the vulnerability does

01Description

HTTP Protocol Stack Remote Code Execution Vulnerability

CISA mandated remediation

02CISA Required Action

Apply updates per vendor instructions.

Key dates

03Disclosure timeline

May 11, 2021 CVE published
October 21, 2025 Record updated