FKIE_CVE-2026-21265
Vulnerability from fkie_nvd - Published: 2026-01-13 18:16 - Updated: 2026-07-30 21:17
Severity
Summary
Windows Secure Boot stores Microsoft certificates in the UEFI KEK and DB. These original certificates are approaching expiration, and devices containing affected certificate versions must update them to maintain Secure Boot functionality and avoid compromising security by losing security fixes related to Windows boot manager or Secure Boot.
The operating system’s certificate update protection mechanism relies on firmware components that might contain defects, which can cause certificate trust updates to fail or behave unpredictably. This leads to potential disruption of the Secure Boot trust chain and requires careful validation and deployment to restore intended security guarantees.
Certificate Authority (CA)
Location
Purpose
Expiration Date
Microsoft Corporation KEK CA 2011
KEK
Signs updates to the DB and DBX
06/24/2026
Microsoft Corporation UEFI CA 2011
DB
Signs 3rd party boot loaders, Option ROMs, etc.
06/27/2026
Microsoft Windows Production PCA 2011
DB
Signs the Windows Boot Manager
10/19/2026
For more information see this CVE and Windows Secure Boot certificate expiration and CA updates.
References
| URL | Tags | ||
|---|---|---|---|
| secure@microsoft.com | https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21265 | Vendor Advisory |
Impacted products
{
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"vendor": "Microsoft",
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"version": "6.2.9200.0",
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"product": "Windows Server 2012 R2",
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"vendor": "Microsoft",
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"product": "Windows Server 2022",
"vendor": "Microsoft",
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"status": "affected",
"version": "10.0.20348.0",
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"product": "Windows Server 2022, 23H2 Edition (Server Core installation)",
"vendor": "Microsoft",
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"vendor": "Microsoft",
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],
"source": "secure@microsoft.com"
}
],
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],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Windows Secure Boot stores Microsoft certificates in the UEFI KEK and DB. These original certificates are approaching expiration, and devices containing affected certificate versions must update them to maintain Secure Boot functionality and avoid compromising security by losing security fixes related to Windows boot manager or Secure Boot.\nThe operating system\u2019s certificate update protection mechanism relies on firmware components that might contain defects, which can cause certificate trust updates to fail or behave unpredictably. This leads to potential disruption of the Secure Boot trust chain and requires careful validation and deployment to restore intended security guarantees.\n\n\n\nCertificate Authority (CA)\nLocation\nPurpose\nExpiration Date\n\n\n\n\nMicrosoft Corporation KEK CA 2011\nKEK\nSigns updates to the DB and DBX\n06/24/2026\n\n\nMicrosoft Corporation UEFI CA 2011\nDB\nSigns 3rd party boot loaders, Option ROMs, etc.\n06/27/2026\n\n\nMicrosoft Windows Production PCA 2011\nDB\nSigns the Windows Boot Manager\n10/19/2026\n\n\n\nFor more information see this CVE and Windows Secure Boot certificate expiration and CA updates."
},
{
"lang": "es",
"value": "Secure Boot de Windows almacena certificados de Microsoft en el KEK y DB de UEFI. Estos certificados originales est\u00e1n pr\u00f3ximos a caducar, y los dispositivos que contienen versiones de certificados afectadas deben actualizarlos para mantener la funcionalidad de Secure Boot y evitar comprometer la seguridad al perder las correcciones de seguridad relacionadas con el gestor de arranque de Windows o Secure Boot.\nEl mecanismo de protecci\u00f3n de actualizaci\u00f3n de certificados del sistema operativo se basa en componentes de firmware que podr\u00edan contener defectos, lo que puede hacer que las actualizaciones de confianza de los certificados fallen o se comporten de manera impredecible. Esto lleva a una posible interrupci\u00f3n de la cadena de confianza de Secure Boot y requiere una validaci\u00f3n y un despliegue cuidadosos para restaurar las garant\u00edas de seguridad previstas.\n\nAutoridad de Certificaci\u00f3n (CA)\nUbicaci\u00f3n\nProp\u00f3sito\nFecha de Vencimiento\n\nMicrosoft Corporation KEK CA 2011\nKEK\nFirma las actualizaciones de la DB y DBX\n24/06/2026\n\nMicrosoft Corporation UEFI CA 2011\nDB\nFirma cargadores de arranque de terceros, ROMs de opci\u00f3n, etc.\n27/06/2026\n\nMicrosoft Windows Production PCA 2011\nDB\nFirma el Gestor de Arranque de Windows\n19/10/2026\n\nPara m\u00e1s informaci\u00f3n, consulte este CVE y el vencimiento de los certificados de Secure Boot de Windows y las actualizaciones de CA."
}
],
"id": "CVE-2026-21265",
"lastModified": "2026-07-30T21:17:13.597",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "HIGH",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 6.4,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "HIGH",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 0.5,
"impactScore": 5.9,
"source": "secure@microsoft.com",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-21265",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-01-14T04:57:08.255762Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-01-13T18:16:25.053",
"references": [
{
"source": "secure@microsoft.com",
"tags": [
"Vendor Advisory"
],
"url": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21265"
}
],
"sourceIdentifier": "secure@microsoft.com",
"vulnStatus": "Analyzed",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-1329"
}
],
"source": "secure@microsoft.com",
"type": "Secondary"
}
]
}
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Sightings
| Author | Source | Type | Date | Other |
|---|
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
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They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.