CVE-2026-21265
Unknown Unknown - Not Provided
Secure Boot Certificate Expiration Causes Trust Chain Disruption

Publication date: 2026-01-13

Last updated on: 2026-01-13

Assigner: Microsoft Corporation

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.
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Meta Information
Published
2026-01-13
Last Modified
2026-01-13
Generated
2026-06-16
AI Q&A
2026-01-14
EPSS Evaluated
2026-06-15
NVD
CVE-2026-21265
Affected Vendors & Products
Showing 2 associated CPEs
Vendor Product Version / Range
microsoft windows *
microsoft windows_boot_manager *
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Exploitability
CWE
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KEV
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CWE ID Description
CWE-1329 The product contains a component that cannot be updated or patched in order to remove vulnerabilities or significant bugs.
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Executive Summary

This vulnerability involves Windows Secure Boot certificates stored in the UEFI KEK and DB that are approaching expiration in 2026. These certificates are critical for maintaining the Secure Boot trust chain, which ensures that only trusted software is loaded during the boot process. If these certificates expire without being updated, Secure Boot functionality can be compromised, potentially allowing security feature bypasses. Additionally, the update mechanism relies on firmware components that may have defects, causing certificate trust updates to fail or behave unpredictably, which can disrupt the Secure Boot trust chain and reduce system security. [1]

Impact Analysis

If the expiring certificates are not updated properly, Secure Boot may fail to function correctly, leading to a loss of security protections during system startup. This can result in the inability to prevent unauthorized or malicious software from loading early in the boot process, increasing the risk of system compromise. Furthermore, defects in firmware components involved in the certificate update process can cause update failures or unpredictable behavior, potentially disrupting the Secure Boot trust chain and exposing the system to security risks. [1]

Detection Guidance

This vulnerability relates to expiring Microsoft certificates in the UEFI KEK and DB used by Windows Secure Boot. Detection involves checking the versions and expiration dates of these certificates on affected devices. While specific commands are not provided, administrators should verify the presence and expiration status of the following certificates: Microsoft Corporation KEK CA 2011, Microsoft Corporation UEFI CA 2011, and Microsoft Windows Production PCA 2011. This can typically be done by inspecting UEFI firmware settings or using Windows tools that report Secure Boot certificate information. Due to the nature of the vulnerability, monitoring firmware and OS logs for certificate update failures or Secure Boot trust chain disruptions may also help detect issues. [1]

Mitigation Strategies

Immediate mitigation steps include updating the expiring Microsoft certificates stored in the UEFI KEK and DB to their latest versions to maintain Secure Boot functionality. Because the certificate update mechanism depends on firmware components that may have defects, it is important to carefully validate and deploy these updates to avoid failures or unpredictable behavior. Ensuring devices receive the official Microsoft updates for Secure Boot certificates and verifying successful installation will help prevent security degradation and maintain the integrity of the Secure Boot trust chain. [1]

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