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CVE-2026-21265

MEDIUM CVSS: 6.4 Published: 2026-01-13 Modified: 2026-07-30

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 Platforms

Microsoft Windows Server 2016Microsoft Windows 11 25H2Microsoft Windows 10 21H2Microsoft Windows 11 24H2Microsoft Windows Server 2019Microsoft Windows 10 22H2Microsoft Windows Server 2025Microsoft Windows Server 2022Microsoft Windows 10 1809Microsoft Windows Server 2012

Weakness Type

CWE-1329

References