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Medium severity6.4NVD Advisory· Published Jan 13, 2026· Updated Jul 30, 2026

CVE-2026-21265

CVE-2026-21265

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. 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.

Affected products

45
  • Microsoft/Windows Secure Bootllm-fuzzy
  • Microsoft/Windowsllm-fuzzy
  • Microsoft/Windows 10 1607cpe-rescue11 versions
    10.0.14393.0+ 10 more
    • (no CPE)range: 10.0.14393.0
    • cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x64:*range: <10.0.14393.8783
    • cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x86:*range: <10.0.14393.8783
    • cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:arm64:*range: <10.0.19044.6809
    • cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x64:*range: <10.0.19044.6809
    • cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:x86:*range: <10.0.19044.6809
    • cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:arm64:*range: <10.0.19045.6809
    • cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:x64:*range: <10.0.19045.6809
    • cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:x86:*range: <10.0.19045.6809
    • (no CPE)range: 10.0.19044.0
    • (no CPE)range: 10.0.19045.0
  • Microsoft/Windows 10 1809cpe-rescue3 versions
    10.0.17763.0+ 2 more
    • (no CPE)range: 10.0.17763.0
    • cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x64:*range: <10.0.17763.8276
    • cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*range: <10.0.17763.8276
  • Microsoft/Windows Server 2012 (Server Core installation)v5
    Range: 6.2.9200.0
  • Microsoft/Windows Server 2012 R2 (Server Core installation)v5
    Range: 6.3.9600.0
  • Microsoft/Windows Server 2016 (Server Core installation)v5
    Range: 10.0.14393.0
  • Microsoft/Windows Server 2019 (Server Core installation)v5
    Range: 10.0.17763.0
  • Microsoft/Windows Server 2022, 23H2 Edition (Server Core installation)v5
    Range: 10.0.25398.0
  • Microsoft/Windows Server 2025 (Server Core installation)v5
    Range: 10.0.26100.0
  • Microsoft/Windows 11 23h23 versions
    cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:arm64:*+ 2 more
    • cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:arm64:*range: <10.0.22631.6491
    • cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:x64:*range: <10.0.22631.6491
    • (no CPE)range: 10.0.22631.0
  • Microsoft/Windows 11 24h23 versions
    cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:arm64:*+ 2 more
    • cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:arm64:*range: <10.0.26100.7623
    • cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:x64:*range: <10.0.26100.7623
    • (no CPE)range: 10.0.26100.0
  • Microsoft/Windows 11 25h23 versions
    cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:arm64:*+ 2 more
    • cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:arm64:*range: <10.0.26200.7623
    • cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:x64:*range: <10.0.26200.7623
    • (no CPE)range: 10.0.26200.0
  • Microsoft/Windows Server 20125 versions
    cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:*+ 4 more
    • cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:*
    • cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:*
    • cpe:2.3:o:microsoft:windows_server_2022_23h2:*:*:*:*:*:*:*:*range: <10.0.25398.2092
    • (no CPE)range: 6.2.9200.0
    • (no CPE)range: 6.3.9600.0
  • Microsoft/Windows Server 20162 versions
    cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*+ 1 more
    • cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*range: <10.0.14393.8783
    • (no CPE)range: 10.0.14393.0
  • Microsoft/Windows Server 20192 versions
    cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*+ 1 more
    • cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*range: <10.0.17763.8276
    • (no CPE)range: 10.0.17763.0
  • Microsoft/Windows Server 20032 versions
    cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*+ 1 more
    • cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*range: <10.0.20348.4648
    • (no CPE)range: 10.0.20348.0
  • Microsoft/Windows Server 20252 versions
    cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*+ 1 more
    • cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*range: <10.0.26100.32230
    • (no CPE)range: 10.0.26100.0
  • Microsoft/Windows 10 version 1607cpe-rescue
    Range: 10.0.22631.0

Patches

Vulnerability mechanics

References

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News mentions

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