CVE-2021-31166
Microsoft HTTP Protocol Stack Remote Code Execution Vulnerability
Does this matter?
Known to be exploited in the wild (CISA KEV, CISA remediation deadline 27 April 2022). Treat as an emergency change: patch or isolate now, then hunt for prior compromise.
Description
HTTP Protocol Stack Remote Code Execution Vulnerability
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 99.87% probability · 100th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Listed 6 April 2022 · due 27 April 2022
- Weakness
- CWE-416
- Affected
- microsoft/windows 10 2004 · microsoft/windows 10 20h2 · microsoft/windows server 2004 · microsoft/windows server 20h2
- Source
- secure@microsoft.com
EPSS 99.9% since 30 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
CISA notes
Apply updates per vendor instructions. https://nvd.nist.gov/vuln/detail/CVE-2021-31166
References
- http://packetstormsecurity.com/files/162722/Microsoft-HTTP-Protocol-Stack-Remote-Code-Execution.htmlThird Party Advisory, VDB Entry
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31166Patch, Vendor Advisory
- http://packetstormsecurity.com/files/162722/Microsoft-HTTP-Protocol-Stack-Remote-Code-Execution.htmlThird Party Advisory, VDB Entry
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31166Patch, Vendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-31166US Government Resource
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.