August 10, 2026

CVE Watchtower


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CVE-2026-21265NVD

Vulnerability Summary

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.
Severity Level
MEDIUM(6.4)
Published Date
Jan 13, 2026
Last Modified
Jul 30, 2026
Exploitation Status
No confirmed exploitation yet
EPSS Score (30-Day)
0.97%Probability
Root Weakness (CWE)
Refer to the official MITRE database for detailed architectural specifications regarding this weakness.
CVSS v3.1 Base Metrics
Attack VectorLocal
Attack ComplexityHigh
Privileges RequiredHigh
User InteractionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh