CVE-2026-21265

Secure Boot Certificate Expiration Security Feature Bypass Vulnerability

CVE-2026-21265 is fixed in 29 products on 1 platform, first by KB5073722, released January 13, 2026. It is not reported as exploited. Patch Radar priority: Routine.

RoutinePublicly disclosed
CVSS
6.4
Important
Exploitation
None reported
Exploitation Less Likely
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0110
65th percentile

<p>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.</p> <p>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.</p> <table> <thead> <tr> <th>Certificate Authority (CA)</th> <th>Location</th> <th>Purpose</th> <th>Expiration Date</th> </tr> </thead> <tbody> <tr> <td>Microsoft Corporation KEK CA 2011</td> <td>KEK</td> <td>Signs updates to the DB and DBX</td> <td>06/24/2026</td> </tr> <tr> <td>Microsoft Corporation UEFI CA 2011</td> <td>DB</td> <td>Signs 3rd party boot loaders, Option ROMs, etc.</td> <td>06/27/2026</td> </tr> <tr> <td>Microsoft Windows Production PCA 2011</td> <td>DB</td> <td>Signs the Windows Boot Manager</td> <td>10/19/2026</td> </tr> </tbody> </table> <p>For more information see this CVE and <a href="https://aka.ms/GetSecureBoot">Windows Secure Boot certificate expiration and CA updates</a>.</p>

Where it's fixed

ProductFixed inFixReleased
Microsoft
Windows 10 Version 1607 for 32-bit Systems 14393.8783 KB5073722 Jan 13, 2026
Windows 10 Version 1607 for x64-based Systems 14393.8783 KB5073722 Jan 13, 2026
Windows 10 Version 1809 for 32-bit Systems 17763.8276 KB5073723 Jan 13, 2026
Windows 10 Version 1809 for x64-based Systems 17763.8276 KB5073723 Jan 13, 2026
Windows 10 Version 21H2 for 32-bit Systems KB5073724 Jan 13, 2026
Windows 10 Version 21H2 for ARM64-based Systems KB5073724 Jan 13, 2026
Windows 10 Version 21H2 for x64-based Systems KB5073724 Jan 13, 2026
Windows 10 Version 22H2 for 32-bit Systems KB5073724 Jan 13, 2026
Windows 10 Version 22H2 for ARM64-based Systems KB5073724 Jan 13, 2026
Windows 10 Version 22H2 for x64-based Systems KB5073724 Jan 13, 2026
Windows 11 Version 23H2 for ARM64-based Systems 22631.6491 KB5073455 Jan 13, 2026
Windows 11 Version 23H2 for x64-based Systems 22631.6491 KB5073455 Jan 13, 2026
Windows 11 Version 24H2 for ARM64-based Systems KB5074109 Jan 13, 2026
Windows 11 Version 24H2 for x64-based Systems KB5074109 Jan 13, 2026
Windows 11 Version 25H2 for ARM64-based Systems KB5074109 Jan 13, 2026
Windows 11 Version 25H2 for x64-based Systems KB5074109 Jan 13, 2026
Windows Server 2012 KB5073698 Jan 13, 2026
Windows Server 2012 (Server Core installation) KB5073698 Jan 13, 2026
Windows Server 2012 R2 KB5073696 Jan 13, 2026
Windows Server 2012 R2 (Server Core installation) KB5073696 Jan 13, 2026
Windows Server 2016 14393.8783 KB5073722 Jan 13, 2026
Windows Server 2016 (Server Core installation) 14393.8783 KB5073722 Jan 13, 2026
Windows Server 2019 17763.8276 KB5073723 Jan 13, 2026
Windows Server 2019 (Server Core installation) 17763.8276 KB5073723 Jan 13, 2026
Windows Server 2022 20348.4648 KB5073457 Jan 13, 2026
Windows Server 2022 (Server Core installation) 20348.4648 KB5073457 Jan 13, 2026
Windows Server 2022, 23H2 Edition (Server Core installation) 25398.2092 KB5073450 Jan 13, 2026
Windows Server 2025 26100.32230 KB5073379 Jan 13, 2026
Windows Server 2025 (Server Core installation) 26100.32230 KB5073379 Jan 13, 2026

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