CVE-2021-31166

HTTP Protocol Stack Remote Code Execution Vulnerability

CVSS v3 9.8 CRITICAL
CVSS v2.0 7.5 HIGH

9.8^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

7.5^/10

CVSS v2.0 : HIGH

Vector : AV:N/AC:L/Au:N/C:P/I:P/A:P

Exploitability : 10.0 / Impact : 6.4

Access Vector NETWORK

Access Complexity LOW

Authentication NONE

Confidentiality Impact PARTIAL

Integrity Impact PARTIAL

Availability Impact PARTIAL

References

Link	Resource
http://packetstormsecurity.com/files/162722/Microsoft-HTTP-Protocol-Stack-Remote-Code-Execution.html	Third Party Advisory VDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31166	Patch Vendor Advisory
http://packetstormsecurity.com/files/162722/Microsoft-HTTP-Protocol-Stack-Remote-Code-Execution.html	Third Party Advisory VDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31166	Patch Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-31166

Configurations

Configuration 1 (hide)

OR	cpe:2.3:o:microsoft:windows_10_2004::::::::
	cpe:2.3:o:microsoft:windows_10_20h2::::::::
	cpe:2.3:o:microsoft:windows_server_2004::::::::
	cpe:2.3:o:microsoft:windows_server_20h2::::::::

History

22 Oct 2025, 00:17

Type	Values Removed	Values Added
References		() https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-31166 -

21 Oct 2025, 20:18

Type	Values Removed	Values Added
References	~~{'url': 'https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-31166', 'source': '134c704f-9b21-4f2e-91b3-4a467353bcc0'}~~

21 Oct 2025, 19:19

Type	Values Removed	Values Added
References		() https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-31166 -

Information

Published : 2021-05-11 19:15

Updated : 2025-10-22 00:17

NVD link : CVE-2021-31166

Mitre link : CVE-2021-31166

CVE.ORG link : CVE-2021-31166

JSON object : View

Products Affected

microsoft

windows_server_20h2
windows_10_2004
windows_server_2004
windows_10_20h2

CWE

CWE-416

Use After Free

{"id": "CVE-2021-31166", "cveTags": [], "metrics": {"cvssMetricV2": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"version": "2.0", "baseScore": 7.5, "accessVector": "NETWORK", "vectorString": "AV:N/AC:L/Au:N/C:P/I:P/A:P", "authentication": "NONE", "integrityImpact": "PARTIAL", "accessComplexity": "LOW", "availabilityImpact": "PARTIAL", "confidentialityImpact": "PARTIAL"}, "acInsufInfo": false, "impactScore": 6.4, "baseSeverity": "HIGH", "obtainAllPrivilege": false, "exploitabilityScore": 10.0, "obtainUserPrivilege": false, "obtainOtherPrivilege": false, "userInteractionRequired": false}], "cvssMetricV31": [{"type": "Secondary", "source": "secure@microsoft.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 9.8, "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 3.9}, {"type": "Secondary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 9.8, "attackVector": "NETWORK", "baseSeverity": "CRITICAL", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 3.9}]}, "published": "2021-05-11T19:15:09.300", "references": [{"url": "http://packetstormsecurity.com/files/162722/Microsoft-HTTP-Protocol-Stack-Remote-Code-Execution.html", "tags": ["Third Party Advisory", "VDB Entry"], "source": "secure@microsoft.com"}, {"url": "https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31166", "tags": ["Patch", "Vendor Advisory"], "source": "secure@microsoft.com"}, {"url": "http://packetstormsecurity.com/files/162722/Microsoft-HTTP-Protocol-Stack-Remote-Code-Execution.html", "tags": ["Third Party Advisory", "VDB Entry"], "source": "af854a3a-2127-422b-91ae-364da2661108"}, {"url": "https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31166", "tags": ["Patch", "Vendor Advisory"], "source": "af854a3a-2127-422b-91ae-364da2661108"}, {"url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-31166", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Modified", "weaknesses": [{"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "CWE-416"}]}, {"type": "Secondary", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "description": [{"lang": "en", "value": "CWE-416"}]}], "descriptions": [{"lang": "en", "value": "HTTP Protocol Stack Remote Code Execution Vulnerability"}, {"lang": "es", "value": "Una vulnerabilidad de Ejecuci\u00f3n de C\u00f3digo Remota de HTTP Protocol Stack"}], "lastModified": "2025-10-22T00:17:35.357", "cisaActionDue": "2022-04-27", "cisaExploitAdd": "2022-04-06", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:microsoft:windows_10_2004:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "F170C517-0312-457D-9108-ECA6638C8223", "versionEndExcluding": "10.0.19041.982"}, {"criteria": "cpe:2.3:o:microsoft:windows_10_20h2:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "957F366C-FD59-479A-A6C5-F93E35436549", "versionEndExcluding": "10.0.19042.982"}, {"criteria": "cpe:2.3:o:microsoft:windows_server_2004:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "BD0A39ED-F4B4-4C2D-BDB4-088426F2377B", "versionEndExcluding": "10.0.19041.982"}, {"criteria": "cpe:2.3:o:microsoft:windows_server_20h2:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "F42A77A0-2B44-4C08-8BBB-851B22AED6E8", "versionEndExcluding": "10.0.19042.982"}], "operator": "OR"}]}], "sourceIdentifier": "secure@microsoft.com", "cisaRequiredAction": "Apply updates per vendor instructions.", "cisaVulnerabilityName": "Microsoft HTTP Protocol Stack Remote Code Execution Vulnerability"}