CVE-2026-21265

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.

• Microsoft Windows 10 1607

  OS
  Microsoft
  < 10.0.14393.8783

• Microsoft Windows 10 1809

  OS
  Microsoft
  < 10.0.17763.8276

• Microsoft Windows 10 21h2

  OS
  Microsoft
  < 10.0.19044.6809

• Microsoft Windows 10 22h2

  OS
  Microsoft
  < 10.0.19045.6809

• Microsoft Windows 11 23h2

  OS
  Microsoft
  < 10.0.22631.6491

• Microsoft Windows 11 24h2

  OS
  Microsoft
  < 10.0.26100.7623

• Microsoft Windows 11 25h2

  OS
  Microsoft
  < 10.0.26200.7623

• Microsoft Windows Server 2012

  OS
  Microsoft
  r2

• Microsoft Windows Server 2016

  OS
  Microsoft
  < 10.0.14393.8783

• Microsoft Windows Server 2019

  OS
  Microsoft
  < 10.0.17763.8276

• Microsoft Windows Server 2022

  OS
  Microsoft
  < 10.0.20348.4648

• Microsoft Windows Server 2022 23h2

  OS
  Microsoft
  < 10.0.25398.2092

• Microsoft Windows Server 2025

  OS
  Microsoft
  < 10.0.26100.32230