CVE-2021-31166VulnerabilityPublished 04/06/2022Updated 10/24/2026
CVE-2021-31166: Microsoft HTTP Protocol Stack Remote Code Execution Vulnerability
Affects Microsoft HTTP Protocol StackSource CISA KEV
Severity
HighNo CVSS score published yet
- Exploitation
Actively exploited – in CISA KEV since 04/06/2022
- KEV deadline
- 04/27/2022
- EPSS
- 99.9% chance of exploitation in 30 days – higher than 99% of CVEs
What to do
CISA required action
Apply updates per vendor instructions.
Description
CVE-2021-31166 is a remote code execution vulnerability in the Microsoft HTTP Protocol Stack (http.sys). This flaw allows attackers to execute arbitrary code remotely by exploiting the vulnerable http.sys component. The vulnerability has been exploited in the wild, indicating active attacks leveraging this issue. No specific affected versions are stated in the provided data. The severity is assessed as high due to the potential for remote code execution and active exploitation.