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CVE-2026-21265— Secure Boot Certificate Expiration Security Feature Bypass Vulnerability

Quick assessment

Affected
Microsoft Windows 10 Version 1607
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Microsoft Windows Secure Boot是美国微软（Microsoft）公司的安全启动。 Microsoft Windows Secure Boot存在安全漏洞。攻击者利用该漏洞可以绕过某些功能。以下产品和版本受到影响：Windows 10 Version 1809 for 32-bit Systems,Windows 10 Version 1809 for x64-based Systems,Windows Server 2019,Windows Server 2019 (Server

CVSS 6.4 · Medium EPSS 1.10% · P65

Affected Version Matrix 20

VendorProduct Version RangeStatus
Microsoft Windows 10 Version 1607 10.0.14393.0< 10.0.14393.8783 affected
Microsoft Windows 10 Version 1809 10.0.17763.0< 10.0.17763.8276 affected
Microsoft Windows 10 Version 21H2 10.0.19044.0< 10.0.19044.6809 affected
Microsoft Windows 10 Version 22H2 10.0.19045.0< 10.0.19045.6809 affected
Microsoft Windows 11 version 23H2 10.0.22631.0< 10.0.22631.6491 affected
Microsoft Windows 11 Version 23H2 10.0.22631.0< 10.0.22631.6491 affected
Microsoft Windows 11 Version 24H2 10.0.26100.0< 10.0.26100.7623 affected
Microsoft Windows 11 Version 25H2 10.0.26200.0< 10.0.26200.7623 affected
Microsoft Windows Server 2012 6.2.9200.0< 6.2.9200.25868 affected
Microsoft Windows Server 2012 (Server Core installation) 6.2.9200.0< 6.2.9200.25868 affected
Microsoft Windows Server 2012 R2 6.3.9600.0< 6.3.9600.22968 affected
Microsoft Windows Server 2012 R2 (Server Core installation) 6.3.9600.0< 6.3.9600.22968 affected
Microsoft Windows Server 2016 10.0.14393.0< 10.0.14393.8783 affected
Microsoft Windows Server 2016 (Server Core installation) 10.0.14393.0< 10.0.14393.8783 affected
Microsoft Windows Server 2019 10.0.17763.0< 10.0.17763.8276 affected
Microsoft Windows Server 2019 (Server Core installation) 10.0.17763.0< 10.0.17763.8276 affected
Microsoft Windows Server 2022 10.0.20348.0< 10.0.20348.4648 affected
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.0< 10.0.25398.2092 affected
Microsoft Windows Server 2025 10.0.26100.0< 10.0.26100.32230 affected
Microsoft Windows Server 2025 (Server Core installation) 10.0.26100.0< 10.0.26100.32230 affected
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I. Basic Information for CVE-2026-21265

Vulnerability Information
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Vulnerability Title
Secure Boot Certificate Expiration Security Feature Bypass Vulnerability
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
CWE-1329
Source: CVE Program / CVE List V5
Vulnerability Title
Microsoft Windows Secure Boot 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Microsoft Windows Secure Boot是美国微软（Microsoft）公司的安全启动。 Microsoft Windows Secure Boot存在安全漏洞。攻击者利用该漏洞可以绕过某些功能。以下产品和版本受到影响：Windows 10 Version 1809 for 32-bit Systems,Windows 10 Version 1809 for x64-based Systems,Windows Server 2019,Windows Server 2019 (Server
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Microsoft Windows 10 Version 1607 10.0.14393.0 ~ 10.0.14393.8783 -
Microsoft Windows 10 Version 1809 10.0.17763.0 ~ 10.0.17763.8276 -
Microsoft Windows 10 Version 21H2 10.0.19044.0 ~ 10.0.19044.6809 -
Microsoft Windows 10 Version 22H2 10.0.19045.0 ~ 10.0.19045.6809 -
Microsoft Windows 11 version 23H2 10.0.22631.0 ~ 10.0.22631.6491 -
Microsoft Windows 11 Version 23H2 10.0.22631.0 ~ 10.0.22631.6491 -
Microsoft Windows 11 Version 24H2 10.0.26100.0 ~ 10.0.26100.7623 -
Microsoft Windows 11 Version 25H2 10.0.26200.0 ~ 10.0.26200.7623 -
Microsoft Windows Server 2012 6.2.9200.0 ~ 6.2.9200.25868 -
Microsoft Windows Server 2012 (Server Core installation) 6.2.9200.0 ~ 6.2.9200.25868 -
Microsoft Windows Server 2012 R2 6.3.9600.0 ~ 6.3.9600.22968 -
Microsoft Windows Server 2012 R2 (Server Core installation) 6.3.9600.0 ~ 6.3.9600.22968 -
Microsoft Windows Server 2016 10.0.14393.0 ~ 10.0.14393.8783 -
Microsoft Windows Server 2016 (Server Core installation) 10.0.14393.0 ~ 10.0.14393.8783 -
Microsoft Windows Server 2019 10.0.17763.0 ~ 10.0.17763.8276 -
Microsoft Windows Server 2019 (Server Core installation) 10.0.17763.0 ~ 10.0.17763.8276 -
Microsoft Windows Server 2022 10.0.20348.0 ~ 10.0.20348.4648 -
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.0 ~ 10.0.25398.2092 -
Microsoft Windows Server 2025 10.0.26100.0 ~ 10.0.26100.32230 -
Microsoft Windows Server 2025 (Server Core installation) 10.0.26100.0 ~ 10.0.26100.32230 -

II. Public POCs for CVE-2026-21265

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III. Intelligence Information for CVE-2026-21265

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Same Patch Batch · Microsoft · 2026-01-13 · 112 CVEs total

CVE-2026-20963 9.8 CRITICAL Microsoft SharePoint Remote Code Execution Vulnerability
CVE-2026-20947 8.8 HIGH Microsoft SharePoint Server Remote Code Execution Vulnerability
CVE-2026-20868 8.8 HIGH Windows Routing and Remote Access Service (RRAS) Remote Code Execution Vulnerability
CVE-2026-20952 8.4 HIGH Microsoft Office Remote Code Execution Vulnerability
CVE-2026-20944 8.4 HIGH Microsoft Word Remote Code Execution Vulnerability
CVE-2026-20953 8.4 HIGH Microsoft Office Remote Code Execution Vulnerability
CVE-2026-20856 8.1 HIGH Windows Server Update Service (WSUS) Remote Code Execution Vulnerability
CVE-2026-20931 8.0 HIGH Windows Telephony Service Elevation of Privilege Vulnerability
CVE-2026-20857 7.8 HIGH Windows Cloud Files Mini Filter Driver Elevation of Privilege Vulnerability
CVE-2026-20924 7.8 HIGH Windows Management Services Elevation of Privilege Vulnerability
CVE-2026-20922 7.8 HIGH Windows NTFS Remote Code Execution Vulnerability
CVE-2026-20843 7.8 HIGH Windows Routing and Remote Access Service (RRAS) Elevation of Privilege Vulnerability
CVE-2026-20920 7.8 HIGH Win32k Elevation of Privilege Vulnerability
CVE-2026-20837 7.8 HIGH Windows Media Remote Code Execution Vulnerability
CVE-2026-21224 7.8 HIGH Azure Connected Machine Agent Elevation of Privilege Vulnerability
CVE-2026-20840 7.8 HIGH Windows NTFS Remote Code Execution Vulnerability
CVE-2026-20956 7.8 HIGH Microsoft Excel Remote Code Execution Vulnerability
CVE-2026-20877 7.8 HIGH Windows Management Services Elevation of Privilege Vulnerability
CVE-2026-20951 7.8 HIGH Microsoft SharePoint Server Remote Code Execution Vulnerability
CVE-2026-20946 7.8 HIGH Microsoft Excel Remote Code Execution Vulnerability

Showing top 20 of 112 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Windows 10 Version 1607
Same vendor: Microsoft
Same weakness: CWE-1329

V. Comments for CVE-2026-21265

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