Exploitation evidence
Known exploited · CISA KEV listed
Added 2022-04-06. Ransomware campaign use: Unknown.
CISA required action: Apply updates per vendor instructions.
CISA due date: 2022-04-27. This is the catalog’s deadline, not an assessment of your organization’s exposure.
KEV checked 13 Nov 2026, 00:20 Jerusalem · Original catalog ↗Reported products and versions
Microsoft / Windows 10 Version 2004
Default status: Not specified
- affected: 10.0.0 to < 10.0.19041.982 (custom)
Microsoft / Windows Server version 2004
Default status: Not specified
- affected: 10.0.0 to < 10.0.19041.982 (custom)
Microsoft / Windows 10 Version 20H2
Default status: Not specified
- affected: 10.0.0 to < 10.0.19042.982 (custom)
Microsoft / Windows Server version 20H2
Default status: Not specified
- affected: 10.0.0 to < 10.0.19042.982 (custom)
Fixes and workarounds
No explicit solution text in the downloaded CVE record. Consult the vendor advisory; unaffected version ranges are shown above as reported, not inferred as a patch recommendation.
Sources and related reporting
Observed change timeline
History begins when Egret first downloads each source. It is not the complete upstream CVE history.
12 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-12",
"epss": 0.99867,
"percentile": 0.99963
}10 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-10",
"epss": 0.99867,
"percentile": 0.99963
}09 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-09",
"epss": 0.99867,
"percentile": 0.99962
}08 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-08",
"epss": 0.99867,
"percentile": 0.99962
}07 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-07",
"epss": 0.99867,
"percentile": 0.99962
}06 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-06",
"epss": 0.99867,
"percentile": 0.99962
}06 Nov 2026, 06:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-05",
"epss": 0.99867,
"percentile": 0.99962
}05 Nov 2026, 12:20 Jerusalem · CVE Program record changed
Stored CNA snapshot at this observation.
{
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"timestamp": "2025-02-07T14:36:57.411562Z",
"version": "2.0.3"
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"url": "http://packetstormsecurity.com/files/162722/Microsoft-HTTP-Protocol-Stack-Remote-Code-Execution.html"
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],
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},
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}04 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-04",
"epss": 0.99867,
"percentile": 0.99962
}03 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-03",
"epss": 0.99867,
"percentile": 0.99963
}03 Nov 2026, 02:22 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-02",
"epss": 0.99867,
"percentile": 0.99963
}03 Nov 2026, 02:22 Jerusalem · CISA KEV status changed
Stored KEV snapshot at this observation.
{
"cveID": "CVE-2021-31166",
"cwes": [
"CWE-416"
],
"dateAdded": "2022-04-06",
"dueDate": "2022-04-27",
"forensicTriage": "No",
"knownRansomwareCampaignUse": "Unknown",
"notes": "https://nvd.nist.gov/vuln/detail/CVE-2021-31166",
"product": "HTTP Protocol Stack",
"requiredAction": "Apply updates per vendor instructions.",
"shortDescription": "Microsoft HTTP Protocol Stack contains a vulnerability in http.sys that allows for remote code execution.",
"vendorProject": "Microsoft",
"vulnerabilityName": "Microsoft HTTP Protocol Stack Remote Code Execution Vulnerability"
}