{"id":"CVE-2026-21265","state":"PUBLISHED","title":"Secure Boot Certificate Expiration Security Feature Bypass Vulnerability","description":"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’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.\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.","publishedAt":"2026-01-13T17:56:04.224Z","updatedAt":"2026-07-30T20:46:20.081Z","severity":{"score":6.4,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C","source":"microsoft"},"assigner":"microsoft","products":["Microsoft Windows 10 Version 1607","Microsoft Windows 10 Version 1809","Microsoft Windows 10 Version 21H2","Microsoft Windows 10 Version 22H2","Microsoft Windows 11 version 23H2","Microsoft Windows 11 Version 23H2","Microsoft Windows 11 Version 24H2","Microsoft Windows 11 Version 25H2","Microsoft Windows Server 2012","Microsoft Windows Server 2012 (Server Core installation)","Microsoft Windows Server 2012 R2","Microsoft Windows Server 2012 R2 (Server Core installation)","Microsoft Windows Server 2016","Microsoft Windows Server 2016 (Server Core installation)","Microsoft Windows Server 2019","Microsoft Windows Server 2019 (Server Core installation)","Microsoft Windows Server 2022","Microsoft Windows Server 2022, 23H2 Edition (Server Core installation)","Microsoft Windows Server 2025","Microsoft Windows Server 2025 (Server Core installation)"],"affected":[{"vendor":"Microsoft","product":"Windows 10 Version 1607","versions":[{"version":"10.0.14393.0","status":"affected","lessThan":"10.0.14393.8783","versionType":"custom"}],"platforms":["32-bit Systems","x64-based Systems"]},{"vendor":"Microsoft","product":"Windows 10 Version 1809","versions":[{"version":"10.0.17763.0","status":"affected","lessThan":"10.0.17763.8276","versionType":"custom"}],"platforms":["32-bit Systems","x64-based Systems"]},{"vendor":"Microsoft","product":"Windows 10 Version 21H2","versions":[{"version":"10.0.19044.0","status":"affected","lessThan":"10.0.19044.6809","versionType":"custom"}],"platforms":["32-bit Systems","ARM64-based Systems","x64-based Systems"]},{"vendor":"Microsoft","product":"Windows 10 Version 22H2","versions":[{"version":"10.0.19045.0","status":"affected","lessThan":"10.0.19045.6809","versionType":"custom"}],"platforms":["32-bit Systems","ARM64-based Systems","x64-based Systems"]},{"vendor":"Microsoft","product":"Windows 11 version 23H2","versions":[{"version":"10.0.22631.0","status":"affected","lessThan":"10.0.22631.6491","versionType":"custom"}],"platforms":["ARM64-based Systems"]},{"vendor":"Microsoft","product":"Windows 11 Version 23H2","versions":[{"version":"10.0.22631.0","status":"affected","lessThan":"10.0.22631.6491","versionType":"custom"}],"platforms":["x64-based Systems"]},{"vendor":"Microsoft","product":"Windows 11 Version 24H2","versions":[{"version":"10.0.26100.0","status":"affected","lessThan":"10.0.26100.7623","versionType":"custom"}],"platforms":["ARM64-based Systems","x64-based Systems"]},{"vendor":"Microsoft","product":"Windows 11 Version 25H2","versions":[{"version":"10.0.26200.0","status":"affected","lessThan":"10.0.26200.7623","versionType":"custom"}],"platforms":["ARM64-based Systems","x64-based Systems"]},{"vendor":"Microsoft","product":"Windows Server 2012","versions":[{"version":"6.2.9200.0","status":"affected","lessThan":"6.2.9200.25868","versionType":"custom"}],"platforms":["x64-based Systems"]},{"vendor":"Microsoft","product":"Windows Server 2012 (Server Core installation)","versions":[{"version":"6.2.9200.0","status":"affected","lessThan":"6.2.9200.25868","versionType":"custom"}],"platforms":["x64-based Systems"]},{"vendor":"Microsoft","product":"Windows Server 2012 R2","versions":[{"version":"6.3.9600.0","status":"affected","lessThan":"6.3.9600.22968","versionType":"custom"}],"platforms":["x64-based Systems"]},{"vendor":"Microsoft","product":"Windows Server 2012 R2 (Server Core installation)","versions":[{"version":"6.3.9600.0","status":"affected","lessThan":"6.3.9600.22968","versionType":"custom"}],"platforms":["x64-based Systems"]},{"vendor":"Microsoft","product":"Windows Server 2016","versions":[{"version":"10.0.14393.0","status":"affected","lessThan":"10.0.14393.8783","versionType":"custom"}],"platforms":["x64-based Systems"]},{"vendor":"Microsoft","product":"Windows Server 2016 (Server Core installation)","versions":[{"version":"10.0.14393.0","status":"affected","lessThan":"10.0.14393.8783","versionType":"custom"}],"platforms":["x64-based Systems"]},{"vendor":"Microsoft","product":"Windows Server 2019","versions":[{"version":"10.0.17763.0","status":"affected","lessThan":"10.0.17763.8276","versionType":"custom"}],"platforms":["x64-based Systems"]},{"vendor":"Microsoft","product":"Windows Server 2019 (Server Core installation)","versions":[{"version":"10.0.17763.0","status":"affected","lessThan":"10.0.17763.8276","versionType":"custom"}],"platforms":["x64-based Systems"]},{"vendor":"Microsoft","product":"Windows Server 2022","versions":[{"version":"10.0.20348.0","status":"affected","lessThan":"10.0.20348.4648","versionType":"custom"}],"platforms":["x64-based Systems"]},{"vendor":"Microsoft","product":"Windows Server 2022, 23H2 Edition (Server Core installation)","versions":[{"version":"10.0.25398.0","status":"affected","lessThan":"10.0.25398.2092","versionType":"custom"}],"platforms":["x64-based Systems"]},{"vendor":"Microsoft","product":"Windows Server 2025","versions":[{"version":"10.0.26100.0","status":"affected","lessThan":"10.0.26100.32230","versionType":"custom"}],"platforms":["x64-based Systems"]},{"vendor":"Microsoft","product":"Windows Server 2025 (Server Core installation)","versions":[{"version":"10.0.26100.0","status":"affected","lessThan":"10.0.26100.32230","versionType":"custom"}],"platforms":["x64-based Systems"]}],"references":["https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21265"],"weaknesses":["CWE-1329"],"ingestedAt":"2026-10-29T20:11:10.572Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/21xxx/CVE-2026-21265.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-21265","state":"PUBLISHED","datePublished":"2026-01-13T17:56:04.224Z","dateUpdated":"2026-07-30T20:46:20.081Z","assignerShortName":"microsoft","assignerOrgId":"f38d906d-7342-40ea-92c1-6c4a2c6478c8","dateReserved":"2025-12-11T21:02:05.738Z"},"containers":{"cna":{"title":"Secure Boot Certificate Expiration Security Feature Bypass Vulnerability","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’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.\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."}],"affected":[{"vendor":"Microsoft","product":"Windows 10 Version 1607","versions":[{"version":"10.0.14393.0","status":"affected","lessThan":"10.0.14393.8783","versionType":"custom"}],"platforms":["32-bit Systems","x64-based Systems"]},{"vendor":"Microsoft","product":"Windows 10 Version 1809","versions":[{"version":"10.0.17763.0","status":"affected","lessThan":"10.0.17763.8276","versionType":"custom"}],"platforms":["32-bit Systems","x64-based Systems"]},{"vendor":"Microsoft","product":"Windows 10 Version 21H2","versions":[{"version":"10.0.19044.0","status":"affected","lessThan":"10.0.19044.6809","versionType":"custom"}],"platforms":["32-bit Systems","ARM64-based Systems","x64-based Systems"]},{"vendor":"Microsoft","product":"Windows 10 Version 22H2","versions":[{"version":"10.0.19045.0","status":"affected","lessThan":"10.0.19045.6809","versionType":"custom"}],"platforms":["32-bit Systems","ARM64-based Systems","x64-based Systems"]},{"vendor":"Microsoft","product":"Windows 11 version 23H2","versions":[{"version":"10.0.22631.0","status":"affected","lessThan":"10.0.22631.6491","versionType":"custom"}],"platforms":["ARM64-based Systems"]},{"vendor":"Microsoft","product":"Windows 11 Version 23H2","versions":[{"version":"10.0.22631.0","status":"affected","lessThan":"10.0.22631.6491","versionType":"custom"}],"platforms":["x64-based Systems"]},{"vendor":"Microsoft","product":"Windows 11 Version 24H2","versions":[{"version":"10.0.26100.0","status":"affected","lessThan":"10.0.26100.7623","versionType":"custom"}],"platforms":["ARM64-based Systems","x64-based Systems"]},{"vendor":"Microsoft","product":"Windows 11 Version 25H2","versions":[{"version":"10.0.26200.0","status":"affected","lessThan":"10.0.26200.7623","versionType":"custom"}],"platforms":["ARM64-based Systems","x64-based Systems"]},{"vendor":"Microsoft","product":"Windows Server 2012","versions":[{"version":"6.2.9200.0","status":"affected","lessThan":"6.2.9200.25868","versionType":"custom"}],"platforms":["x64-based Systems"]},{"vendor":"Microsoft","product":"Windows Server 2012 (Server Core 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