Exploitation evidence
Known exploited · CISA KEV listed
Added 2026-02-10. Ransomware campaign use: Unknown.
CISA required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CISA due date: 2026-03-03. 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 1607
Default status: Not specified
- affected: 10.0.14393.0 to < 10.0.14393.8868 (custom)
Microsoft / Windows 10 Version 1809
Default status: Not specified
- affected: 10.0.17763.0 to < 10.0.17763.8389 (custom)
Microsoft / Windows 10 Version 21H2
Default status: Not specified
- affected: 10.0.19044.0 to < 10.0.19044.6937 (custom)
Microsoft / Windows 10 Version 22H2
Default status: Not specified
- affected: 10.0.19045.0 to < 10.0.19045.6937 (custom)
Microsoft / Windows 11 version 22H3
Default status: Not specified
- affected: 10.0.22631.0 to < 10.0.22631.6649 (custom)
Microsoft / Windows 11 Version 23H2
Default status: Not specified
- affected: 10.0.22631.0 to < 10.0.22631.6649 (custom)
Microsoft / Windows 11 Version 24H2
Default status: Not specified
- affected: 10.0.26100.0 to < 10.0.26100.7840 (custom)
Microsoft / Windows 11 Version 25H2
Default status: Not specified
- affected: 10.0.26200.0 to < 10.0.26200.7840 (custom)
Microsoft / Windows 11 version 26H1
Default status: Not specified
- affected: 10.0.28000.0 to < 10.0.28000.1575 (custom)
Microsoft / Windows 11 Version 26H1
Default status: Not specified
- affected: 10.0.28000.0 to < 10.0.28000.1575 (custom)
Microsoft / Windows Server 2012
Default status: Not specified
- affected: 6.2.9200.0 to < 6.2.9200.25923 (custom)
Microsoft / Windows Server 2012 (Server Core installation)
Default status: Not specified
- affected: 6.2.9200.0 to < 6.2.9200.25923 (custom)
Microsoft / Windows Server 2012 R2
Default status: Not specified
- affected: 6.3.9600.0 to < 6.3.9600.23022 (custom)
Microsoft / Windows Server 2012 R2 (Server Core installation)
Default status: Not specified
- affected: 6.3.9600.0 to < 6.3.9600.23022 (custom)
Microsoft / Windows Server 2016
Default status: Not specified
- affected: 10.0.14393.0 to < 10.0.14393.8868 (custom)
Microsoft / Windows Server 2016 (Server Core installation)
Default status: Not specified
- affected: 10.0.14393.0 to < 10.0.14393.8868 (custom)
Microsoft / Windows Server 2019
Default status: Not specified
- affected: 10.0.17763.0 to < 10.0.17763.8389 (custom)
Microsoft / Windows Server 2019 (Server Core installation)
Default status: Not specified
- affected: 10.0.17763.0 to < 10.0.17763.8389 (custom)
Microsoft / Windows Server 2022
Default status: Not specified
- affected: 10.0.20348.0 to < 10.0.20348.4773 (custom)
Microsoft / Windows Server 2022, 23H2 Edition (Server Core installation)
Default status: Not specified
- affected: 10.0.25398.0 to < 10.0.25398.2149 (custom)
Microsoft / Windows Server 2025
Default status: Not specified
- affected: 10.0.26100.0 to < 10.0.26100.32370 (custom)
Microsoft / Windows Server 2025 (Server Core installation)
Default status: Not specified
- affected: 10.0.26100.0 to < 10.0.26100.32370 (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
CVE Program record ↗ · Download tracked evidence as JSON
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21513
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-21513
- https://www.vicarius.io/vsociety/posts/cve-2026-21513-detection-script-security-feature-bypass-vulnerability-in-mshtml-framework
- https://www.vicarius.io/vsociety/posts/cve-2026-21513-mitigation-script-security-feature-bypass-vulnerability-in-mshtml-framework
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": 0.15852,
"percentile": 0.96927
}10 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-10",
"epss": 0.15852,
"percentile": 0.96907
}09 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-09",
"epss": 0.15852,
"percentile": 0.96903
}08 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-08",
"epss": 0.15852,
"percentile": 0.96902
}07 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-07",
"epss": 0.15852,
"percentile": 0.969
}06 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-06",
"epss": 0.15852,
"percentile": 0.96896
}06 Nov 2026, 06:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-05",
"epss": 0.15852,
"percentile": 0.96894
}04 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-04",
"epss": 0.15852,
"percentile": 0.96892
}03 Nov 2026, 18:20 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-03",
"epss": 0.15852,
"percentile": 0.96887
}03 Nov 2026, 12:20 Jerusalem · CVE Program record changed
Stored CNA snapshot at this observation.
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-21513",
"options": [
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},
{
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{
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}
],
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"timestamp": "2026-02-11T04:55:53.740962Z",
"version": "2.0.3"
},
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},
{
"other": {
"content": {
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}
],
"timeline": [
{
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"time": "2026-02-10T00:00:00.000Z",
"value": "CVE-2026-21513 added to CISA KEV"
}
],
"title": "CISA ADP Vulnrichment"
},
{
"providerMetadata": {
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"orgId": "af854a3a-2127-422b-91ae-364da2661108",
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{
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},
{
"url": "https://www.vicarius.io/vsociety/posts/cve-2026-21513-mitigation-script-security-feature-bypass-vulnerability-in-mshtml-framework"
}
],
"title": "CVE Program Container",
"x_generator": {
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],
"cna": {
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"product": "Windows 11 Version 24H2",
"vendor": "Microsoft",
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{
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"status": "affected",
"version": "10.0.26100.0",
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]
},
{
"product": "Windows 11 Version 25H2",
"vendor": "Microsoft",
"versions": [
{
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"status": "affected",
"version": "10.0.26200.0",
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},
{
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"product": "Windows 11 version 26H1",
"vendor": "Microsoft",
"versions": [
{
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"status": "affected",
"version": "10.0.28000.0",
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},
{
"product": "Windows 11 Version 26H1",
"vendor": "Microsoft",
"versions": [
{
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"status": "affected",
"version": "10.0.28000.0",
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},
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"product": "Windows Server 2012",
"vendor": "Microsoft",
"versions": [
{
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"status": "affected",
"version": "6.2.9200.0",
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},
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"product": "Windows Server 2012 (Server Core installation)",
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{
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"status": "affected",
"version": "6.2.9200.0",
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},
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"platforms": [
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"product": "Windows Server 2012 R2",
"vendor": "Microsoft",
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{
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"status": "affected",
"version": "6.3.9600.0",
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},
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"product": "Windows Server 2012 R2 (Server Core installation)",
"vendor": "Microsoft",
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"status": "affected",
"version": "6.3.9600.0",
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]
},
{
"platforms": [
"x64-based Systems"
],
"product": "Windows Server 2016",
"vendor": "Microsoft",
"versions": [
{
"lessThan": "10.0.14393.8868",
"status": "affected",
"version": "10.0.14393.0",
"versionType": "custom"
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]
},
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"product": "Windows Server 2016 (Server Core installation)",
"vendor": "Microsoft",
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"status": "affected",
"version": "10.0.14393.0",
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},
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"product": "Windows Server 2019",
"vendor": "Microsoft",
"versions": [
{
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"status": "affected",
"version": "10.0.17763.0",
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},
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"product": "Windows Server 2019 (Server Core installation)",
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"version": "10.0.17763.0",
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"product": "Windows Server 2022",
"vendor": "Microsoft",
"versions": [
{
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"status": "affected",
"version": "10.0.20348.0",
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},
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"product": "Windows Server 2022, 23H2 Edition (Server Core installation)",
"vendor": "Microsoft",
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"version": "10.0.25398.0",
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"product": "Windows Server 2025",
"vendor": "Microsoft",
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"status": "affected",
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],
"cpeApplicability": [
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},
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},
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},
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},
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}
],
"datePublic": "2026-02-10T16:00:00.000Z",
"descriptions": [
{
"lang": "en-US",
"value": "Protection mechanism failure in MSHTML Framework allows an unauthorized attacker to bypass a security feature over a network."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 8.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C",
"version": "3.1"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en-US",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-693",
"description": "CWE-693: Protection Mechanism Failure",
"lang": "en-US",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-19T16:25:57.019Z",
"orgId": "f38d906d-7342-40ea-92c1-6c4a2c6478c8",
"shortName": "microsoft"
},
"references": [
{
"name": "MSHTML Framework Security Feature Bypass Vulnerability",
"tags": [
"vendor-advisory",
"patch"
],
"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21513"
}
],
"title": "MSHTML Framework Security Feature Bypass Vulnerability"
}
},
"cveMetadata": {
"assignerOrgId": "f38d906d-7342-40ea-92c1-6c4a2c6478c8",
"assignerShortName": "microsoft",
"cveId": "CVE-2026-21513",
"datePublished": "2026-02-10T17:51:26.733Z",
"dateReserved": "2025-12-30T18:10:54.845Z",
"dateUpdated": "2026-08-19T16:25:57.019Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}03 Nov 2026, 02:22 Jerusalem · EPSS observation updated
Stored EPSS snapshot at this observation.
{
"date": "2026-11-02",
"epss": 0.15852,
"percentile": 0.96883
}03 Nov 2026, 02:22 Jerusalem · CISA KEV status changed
Stored KEV snapshot at this observation.
{
"cveID": "CVE-2026-21513",
"cwes": [
"CWE-693"
],
"dateAdded": "2026-02-10",
"dueDate": "2026-03-03",
"forensicTriage": "No",
"knownRansomwareCampaignUse": "Unknown",
"notes": "https://msrc.microsoft.com/update-guide/advisory/CVE-2026-21513 ; https://nvd.nist.gov/vuln/detail/CVE-2026-21513",
"product": "Windows",
"requiredAction": "Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.",
"shortDescription": "Microsoft MSHTML Framework contains a protection mechanism failure vulnerability that could allow an unauthorized attacker to bypass a security feature over a network.",
"vendorProject": "Microsoft",
"vulnerabilityName": "Microsoft MSHTML Framework Protection Mechanism Failure Vulnerability"
}