CVE-2021-31166
CRITICALCVSS 9.8/10Actively ExploitedEPSS 99.66%
Last modified
CVE-2021-31166 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. HTTP Protocol Stack Remote Code Execution Vulnerability. CISA has confirmed active exploitation in the wild. EPSS estimates a 99.66% chance of exploitation in the next 30 days.
Description
HTTP Protocol Stack Remote Code Execution Vulnerability
Metrics
Exploitation Status
This vulnerability is listed in CISA’s Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. Federal agencies must remediate by .
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Windows 10 2004 | < 10.0.19041.982 |
| Microsoft | Windows 10 20h2 | < 10.0.19042.982 |
| Microsoft | Windows Server 2004 | < 10.0.19041.982 |
| Microsoft | Windows Server 20h2 | < 10.0.19042.982 |
References
- https://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://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
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2021-31166?
HTTP Protocol Stack Remote Code Execution Vulnerability
How severe is CVE-2021-31166?
CVE-2021-31166 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 99.66% probability of exploitation in the next 30 days. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog.
How do I fix CVE-2021-31166?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
Related CVEs from 2021
- CVE-2021-31159Zoho ManageEngine ServiceDesk Plus MSP before 10519 is vulne…5.3
- CVE-2021-3116before_upstream_connection in AuthPlugin in http/proxy/auth.…7.5
- CVE-2021-31160Zoho ManageEngine ServiceDesk Plus MSP before 10521 allows a…7.5
- CVE-2021-31162In the standard library in Rust before 1.52.0, a double free…9.8
- CVE-2021-31164Apache Unomi prior to version 1.5.5 allows CRLF log injectio…7.5
- CVE-2021-31165Windows Container Manager Service Elevation of Privilege Vul…7.8
- CVE-2021-31167Windows Container Manager Service Elevation of Privilege Vul…7.8
- CVE-2021-31168Windows Container Manager Service Elevation of Privilege Vul…7.8
- CVE-2021-31169Windows Container Manager Service Elevation of Privilege Vul…7.8
- CVE-2021-31170Windows Graphics Component Elevation of Privilege Vulnerabil…7.8
- CVE-2021-31171Microsoft SharePoint Information Disclosure Vulnerability4.1
- CVE-2021-31172Microsoft SharePoint Server Spoofing Vulnerability7.1
Are you affected by CVE-2021-31166?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST