CVE-2026-21265 (GCVE-0-2026-21265)
Vulnerability from cvelistv5
Published
2026-01-13 17:56
Modified
2026-04-01 13:48
Severity ?
VLAI Severity ?
EPSS score ?
CWE
- CWE-1329 - - Reliance on Component That is Not Updateable
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
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Impacted products
| Vendor | Product | Version | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Microsoft | Windows 10 Version 1607 |
Version: 10.0.14393.0 < 10.0.14393.8783 |
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\"version\": \"10.0.17763.0\", \"lessThan\": \"10.0.17763.8276\", \"versionType\": \"custom\"}], \"platforms\": [\"x64-based Systems\"]}, {\"vendor\": \"Microsoft\", \"product\": \"Windows Server 2022\", \"versions\": [{\"status\": \"affected\", \"version\": \"10.0.20348.0\", \"lessThan\": \"10.0.20348.4648\", \"versionType\": \"custom\"}], \"platforms\": [\"x64-based Systems\"]}, {\"vendor\": \"Microsoft\", \"product\": \"Windows Server 2022, 23H2 Edition (Server Core installation)\", \"versions\": [{\"status\": \"affected\", \"version\": \"10.0.25398.0\", \"lessThan\": \"10.0.25398.2092\", \"versionType\": \"custom\"}], \"platforms\": [\"x64-based Systems\"]}, {\"vendor\": \"Microsoft\", \"product\": \"Windows Server 2025\", \"versions\": [{\"status\": \"affected\", \"version\": \"10.0.26100.0\", \"lessThan\": \"10.0.26100.32230\", \"versionType\": \"custom\"}], \"platforms\": [\"x64-based Systems\"]}, {\"vendor\": \"Microsoft\", \"product\": \"Windows Server 2025 (Server Core installation)\", \"versions\": [{\"status\": \"affected\", \"version\": \"10.0.26100.0\", \"lessThan\": \"10.0.26100.32230\", \"versionType\": \"custom\"}], \"platforms\": [\"x64-based Systems\"]}], \"datePublic\": \"2026-01-13T16:00:00.000Z\", \"references\": [{\"url\": \"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21265\", \"name\": \"Secure Boot Certificate Expiration Security Feature Bypass Vulnerability\", \"tags\": [\"vendor-advisory\", \"patch\"]}], \"descriptions\": [{\"lang\": \"en-US\", \"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.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en-US\", \"type\": \"CWE\", \"cweId\": \"CWE-1329\", \"description\": \"CWE-1329 - Reliance on Component That is Not Updateable\"}]}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*\", \"vulnerable\": true, \"versionEndExcluding\": \"10.0.17763.8276\", \"versionStartIncluding\": \"10.0.17763.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"10.0.17763.8276\", \"versionStartIncluding\": \"10.0.17763.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"10.0.17763.8276\", \"versionStartIncluding\": \"10.0.17763.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"10.0.20348.4648\", \"versionStartIncluding\": \"10.0.20348.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_10_21H2:*:*:*:*:*:*:x86:*\", \"vulnerable\": true, \"versionEndExcluding\": \"10.0.19044.6809\", \"versionStartIncluding\": \"10.0.19044.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_10_22H2:*:*:*:*:*:*:x64:*\", \"vulnerable\": true, \"versionEndExcluding\": \"10.0.19045.6809\", \"versionStartIncluding\": \"10.0.19045.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"10.0.26100.32230\", \"versionStartIncluding\": \"10.0.26100.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_11_25H2:*:*:*:*:*:*:arm64:*\", \"vulnerable\": true, \"versionEndExcluding\": \"10.0.26200.7623\", \"versionStartIncluding\": \"10.0.26200.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_11_23H2:*:*:*:*:*:*:arm64:*\", \"vulnerable\": true, \"versionEndExcluding\": \"10.0.22631.6491\", \"versionStartIncluding\": \"10.0.22631.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_11_23H2:*:*:*:*:*:*:x64:*\", \"vulnerable\": true, \"versionEndExcluding\": \"10.0.22631.6491\", \"versionStartIncluding\": \"10.0.22631.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_server_23h2:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"10.0.25398.2092\", \"versionStartIncluding\": \"10.0.25398.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_11_24H2:*:*:*:*:*:*:arm64:*\", \"vulnerable\": true, \"versionEndExcluding\": \"10.0.26100.7623\", \"versionStartIncluding\": \"10.0.26100.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"10.0.26100.32230\", \"versionStartIncluding\": \"10.0.26100.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x86:*\", \"vulnerable\": true, \"versionEndExcluding\": \"10.0.14393.8783\", \"versionStartIncluding\": \"10.0.14393.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"10.0.14393.8783\", \"versionStartIncluding\": \"10.0.14393.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"10.0.14393.8783\", \"versionStartIncluding\": \"10.0.14393.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_server_2012:*:*:*:*:*:*:x64:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.2.9200.25868\", \"versionStartIncluding\": \"6.2.9200.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_server_2012:*:*:*:*:*:*:x64:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.2.9200.25868\", \"versionStartIncluding\": \"6.2.9200.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_server_2012_R2:*:*:*:*:*:*:x64:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.3.9600.22968\", \"versionStartIncluding\": \"6.3.9600.0\"}, {\"criteria\": \"cpe:2.3:o:microsoft:windows_server_2012_R2:*:*:*:*:*:*:x64:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.3.9600.22968\", \"versionStartIncluding\": \"6.3.9600.0\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"f38d906d-7342-40ea-92c1-6c4a2c6478c8\", \"shortName\": \"microsoft\", \"dateUpdated\": \"2026-04-01T13:48:13.618Z\"}}}",
"cveMetadata": "{\"cveId\": \"CVE-2026-21265\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-04-01T13:48:13.618Z\", \"dateReserved\": \"2025-12-11T21:02:05.738Z\", \"assignerOrgId\": \"f38d906d-7342-40ea-92c1-6c4a2c6478c8\", \"datePublished\": \"2026-01-13T17:56:04.224Z\", \"assignerShortName\": \"microsoft\"}",
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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