CVE-2021-31166CISA KEV

Microsoft HTTP Protocol Stack Remote Code Execution Vulnerability

Severity unknownCVSS unknownCheck the vendor advisory for fixed versions

CISA lists this Microsoft vulnerability as known exploited. Its MSRC release detail is outside this installation's collected history.

CISA KEV Check MSRC

CISA catalog record

Microsoft HTTP Protocol Stack contains a vulnerability in http.sys that allows for remote code execution.

Product: HTTP Protocol Stack
Added to KEV: 6 Apr 2022
Federal remediation due: 27 Apr 2022
Known ransomware use: Not reported

Page history

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Field-level log (2)

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23 Oct 2026 · 09:33:49 UTC Source coverage: cisa-kevIncomplete → Current
23 Oct 2026 · 08:31:50 UTC Source coverage: cisa-kevCurrent → Incomplete

Explore global source statements, affected packages and advisory history for CVE-2021-31166. The catalog has a separate collection scope from Microsoft release records.

More advisories, affected versions and source history

cve-program · CVE-2021-31166

Published

Windows 10 Version 2004

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "Microsoft",
                    "product": "Windows 10 Version 2004",
                    "cpes": [
                        "cpe:2.3:o:microsoft:windows_10_1809:10.0.19041.982:*:*:*:*:*:x64:*"
                    ],
                    "platforms": [
                        "32-bit Systems",
                        "ARM64-based Systems",
                        "x64-based Systems"
                    ],
                    "versions": [
                        {
                            "version": "10.0.0",
                            "lessThan": "10.0.19041.982",
                            "versionType": "custom",
                            "status": "affected"
                        }
                    ]
                }

Windows Server version 2004

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "Microsoft",
                    "product": "Windows Server version 2004",
                    "cpes": [
                        "cpe:2.3:o:microsoft:windows_server_2004:10.0.19041.982:*:*:*:*:*:*:*"
                    ],
                    "platforms": [
                        "x64-based Systems"
                    ],
                    "versions": [
                        {
                            "version": "10.0.0",
                            "lessThan": "10.0.19041.982",
                            "versionType": "custom",
                            "status": "affected"
                        }
                    ]
                }

Windows 10 Version 20H2

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "Microsoft",
                    "product": "Windows 10 Version 20H2",
                    "cpes": [
                        "cpe:2.3:o:microsoft:windows_10_20H2:10.0.19042.982:*:*:*:*:*:x86:*",
                        "cpe:2.3:o:microsoft:windows_10_20H2:10.0.19042.982:*:*:*:*:*:arm64:*"
                    ],
                    "platforms": [
                        "32-bit Systems",
                        "ARM64-based Systems"
                    ],
                    "versions": [
                        {
                            "version": "10.0.0",
                            "lessThan": "10.0.19042.982",
                            "versionType": "custom",
                            "status": "affected"
                        }
                    ]
                }

Windows Server version 20H2

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "Microsoft",
                    "product": "Windows Server version 20H2",
                    "cpes": [
                        "cpe:2.3:o:microsoft:windows_server_20H2:10.0.19042.982:*:*:*:*:*:*:*"
                    ],
                    "platforms": [
                        "x64-based Systems"
                    ],
                    "versions": [
                        {
                            "version": "10.0.0",
                            "lessThan": "10.0.19042.982",
                            "versionType": "custom",
                            "status": "affected"
                        }
                    ]
                }

Original source record · Cite this exact observation · Complete original publisher JSON