Is CVE-2021-31166 actively exploited?

Yes. CVE-2021-31166 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, which means exploitation in the wild has been confirmed.

Can CVE-2021-31166 be exploited remotely?

The attack vector of CVE-2021-31166 has not been classified yet.

What is the CVSS score of CVE-2021-31166?

CVE-2021-31166 has not received a CVSS score yet.

HOME VULNERABILITIESCVE-2021-31166

HIGHCISA KEVIN THE WILD

CVE-2021-31166

Published: April 6, 2022

EPSS:93.07%probability of exploitation in 30 daysPercentile:99.8th

Official Description

Microsoft HTTP Protocol Stack contains a vulnerability in http.sys that allows for remote code execution.

NVD Source

CISA KEV Advisory

Microsoft HTTP Protocol Stack Remote Code Execution Vulnerability

Microsoft HTTP Protocol Stack contains a vulnerability in http.sys that allows for remote code execution.

Added to KEV: 2022-04-06Federal patch deadline: 2022-04-27

Required Action (CISA)

Apply updates per vendor instructions.

Risk Analysis

A critical vulnerability exists in the Microsoft HTTP Protocol Stack (http.sys) that enables remote code execution. This flaw is highly likely to be exploited, as indicated by its EPSS score of 0.93069, and has been confirmed as actively exploited by its inclusion in CISA's KEV catalog. This makes it an urgent threat to affected Windows systems.

This vulnerability is actively exploited in the wild, meaning attackers are currently leveraging it to compromise systems. The flaw is remotely exploitable, allowing for attacks without requiring local access.

Recommended Action

Apply the latest security updates from Microsoft to patch the http.sys component. Ensure all systems are kept up-to-date with the latest security patches to mitigate this and similar remote code execution vulnerabilities.

Generated by the CTIWATCH analysis pipeline from this CVE's metadata (CVSS, EPSS, KEV status, exploit intelligence). Verify against vendor advisories before acting.

Technical Analysis

CVE-2021-31166 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

CISA has added CVE-2021-31166 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.