How severe is CVE-2021-31166?

CVE-2021-31166 has a CVSS 3.1 base score of 9.8 (CRITICAL). EPSS estimates a 99.9% probability of exploitation in the next 30 days. It is listed in the CISA Known Exploited Vulnerabilities catalog.

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

CISA Known Exploited Vulnerabilities

Microsoft HTTP Protocol Stack Remote Code Execution Vulnerability is confirmed as actively exploited and is listed in the CISA KEV catalog.

Added to KEV

2022-04-06

Remediation due

2022-04-27

Required action
Apply updates per vendor instructions.

CISA notes
https://nvd.nist.gov/vuln/detail/CVE-2021-31166

Description

HTTP Protocol Stack Remote Code Execution Vulnerability

Severity

CVSS 3.1 · CNA9.8 CRITICAL

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

SSVC · CISA-ADP

Exploitationactive

Automatableyes

Technical impacttotal

Affected Products

Vendor	Product	Affected versions
Microsoft	Windows 10 Version 2004	10.0.0 to <10.0.19041.982
Microsoft	Windows Server version 2004	10.0.0 to <10.0.19041.982
Microsoft	Windows 10 Version 20H2	10.0.0 to <10.0.19042.982
Microsoft	Windows Server version 20H2	10.0.0 to <10.0.19042.982

References

2 Links

Other references

Record Details

Published

2021-05-11

Last updated

2025-10-21

Assigner (CNA)

microsoft

Credited to

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CVE record data © The MITRE Corporation, used under the CVE Terms of Use. Exploited-in-the-wild data from the CISA Known Exploited Vulnerabilities catalog (CC0). Exploit prediction scores by FIRST EPSS (first.org/epss). This site is not endorsed or certified by MITRE, NVD, CISA, or FIRST.