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CVE-2026-21265

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CVE-2026-21265

Published: Jan 13, 2026

Modified: Apr 1, 2026

PUBLISHED

CVSS v3.1

6.4

MEDIUM

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.

VendorProductVersions

Microsoft

Windows 10 Version 1607

affected
10.0.14393.0 - < 10.0.14393.8783

Microsoft

Windows 10 Version 1809

affected
10.0.17763.0 - < 10.0.17763.8276

Microsoft

Windows 10 Version 21H2

affected
10.0.19044.0 - < 10.0.19044.6809

Microsoft

Windows 10 Version 22H2

affected
10.0.19045.0 - < 10.0.19045.6809

Microsoft

Windows 11 version 22H3

affected
10.0.22631.0 - < 10.0.22631.6491

Microsoft

Windows 11 Version 23H2

affected
10.0.22631.0 - < 10.0.22631.6491

Microsoft

Windows 11 Version 24H2

affected
10.0.26100.0 - < 10.0.26100.7623

Microsoft

Windows 11 Version 25H2

affected
10.0.26200.0 - < 10.0.26200.7623

Microsoft

Windows Server 2012

affected
6.2.9200.0 - < 6.2.9200.25868

Microsoft

Windows Server 2012 (Server Core installation)

affected
6.2.9200.0 - < 6.2.9200.25868

Microsoft

Windows Server 2012 R2

affected
6.3.9600.0 - < 6.3.9600.22968

Microsoft

Windows Server 2012 R2 (Server Core installation)

affected
6.3.9600.0 - < 6.3.9600.22968

Microsoft

Windows Server 2016

affected
10.0.14393.0 - < 10.0.14393.8783

Microsoft

Windows Server 2016 (Server Core installation)

affected
10.0.14393.0 - < 10.0.14393.8783

Microsoft

Windows Server 2019

affected
10.0.17763.0 - < 10.0.17763.8276

Microsoft

Windows Server 2019 (Server Core installation)

affected
10.0.17763.0 - < 10.0.17763.8276

Microsoft

Windows Server 2022

affected
10.0.20348.0 - < 10.0.20348.4648

Microsoft

Windows Server 2022, 23H2 Edition (Server Core installation)

affected
10.0.25398.0 - < 10.0.25398.2092

Microsoft

Windows Server 2025

affected
10.0.26100.0 - < 10.0.26100.32230

Microsoft

Windows Server 2025 (Server Core installation)

affected
10.0.26100.0 - < 10.0.26100.32230

Weaknesses (CWE)

CWE-1329

CVSS v3.1 Details

CVSS v3.1 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

Attack Vector

Local

Attack Complexity

High

Privileges Required

High

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

References

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