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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.

Security Impact Summary

This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 6.4, requiring local system access to exploit but requires specific conditions to be met without requiring user interaction . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), and availability (service disruption) for affected systems. Impacting 13 products from microsoft, from microsoft, from microsoft and 10 others, organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2026, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.

Published

2026-01-13T18:16:25.053

Last Modified

2026-01-14T20:23:43.417

Status

Analyzed

Source

[email protected]

Severity

CVSSv3.1: 6.4 (MEDIUM)

Weaknesses
  • Type: Secondary
    CWE-1329
Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Operating System microsoft windows_10_1607 < 10.0.14393.8783 Yes
Operating System microsoft windows_10_1607 < 10.0.14393.8783 Yes
Operating System microsoft windows_10_1809 < 10.0.17763.8276 Yes
Operating System microsoft windows_10_1809 < 10.0.17763.8276 Yes
Operating System microsoft windows_10_21h2 < 10.0.19044.6809 Yes
Operating System microsoft windows_10_21h2 < 10.0.19044.6809 Yes
Operating System microsoft windows_10_21h2 < 10.0.19044.6809 Yes
Operating System microsoft windows_10_22h2 < 10.0.19045.6809 Yes
Operating System microsoft windows_10_22h2 < 10.0.19045.6809 Yes
Operating System microsoft windows_10_22h2 < 10.0.19045.6809 Yes
Operating System microsoft windows_11_23h2 < 10.0.22631.6491 Yes
Operating System microsoft windows_11_23h2 < 10.0.22631.6491 Yes
Operating System microsoft windows_11_24h2 < 10.0.26100.7623 Yes
Operating System microsoft windows_11_24h2 < 10.0.26100.7623 Yes
Operating System microsoft windows_11_25h2 < 10.0.26200.7623 Yes
Operating System microsoft windows_11_25h2 < 10.0.26200.7623 Yes
Operating System microsoft windows_server_2012 - Yes
Operating System microsoft windows_server_2012 r2 Yes
Operating System microsoft windows_server_2016 < 10.0.14393.8783 Yes
Operating System microsoft windows_server_2019 < 10.0.17763.8276 Yes
Operating System microsoft windows_server_2022 < 10.0.20348.4648 Yes
Operating System microsoft windows_server_2022_23h2 < 10.0.25398.2092 Yes
Operating System microsoft windows_server_2025 < 10.0.26100.32230 Yes
References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For microsoft's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.