Secure Boot Certificate Expiration Security Feature Bypass Vulnerability
Summary
| CVE | CVE-2026-21265 |
|---|---|
| State | PUBLISHED |
| Assigner | microsoft |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-01-13 18:16:25 UTC |
| Updated | 2026-07-30 21:17:13 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 6.4 MEDIUM from [email protected]
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.009650000 probability, percentile 0.582150000 (date 2026-08-01)
Problem Types: CWE-1329 | CWE-1329 CWE-1329 - Reliance on Component That is Not Updateable
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Secondary | 6.4 | MEDIUM | CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | CNA | CVSS | 6.4 | MEDIUM | CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C |
CVSS v3.1 Breakdown
Attack Vector
LocalAttack Complexity
HighPrivileges Required
HighUser Interaction
NoneScope
UnchangedConfidentiality
HighIntegrity
HighAvailability
HighCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Operating System | Microsoft | Windows 10 1607 | All | All | All | All |
| Operating System | Microsoft | Windows 10 1607 | All | All | All | All |
| Operating System | Microsoft | Windows 10 1809 | All | All | All | All |
| Operating System | Microsoft | Windows 10 1809 | All | All | All | All |
| Operating System | Microsoft | Windows 10 21h2 | All | All | All | All |
| Operating System | Microsoft | Windows 10 21h2 | All | All | All | All |
| Operating System | Microsoft | Windows 10 21h2 | All | All | All | All |
| Operating System | Microsoft | Windows 10 22h2 | All | All | All | All |
| Operating System | Microsoft | Windows 10 22h2 | All | All | All | All |
| Operating System | Microsoft | Windows 10 22h2 | All | All | All | All |
| Operating System | Microsoft | Windows 11 23h2 | All | All | All | All |
| Operating System | Microsoft | Windows 11 23h2 | All | All | All | All |
| Operating System | Microsoft | Windows 11 24h2 | All | All | All | All |
| Operating System | Microsoft | Windows 11 24h2 | All | All | All | All |
| Operating System | Microsoft | Windows 11 25h2 | All | All | All | All |
| Operating System | Microsoft | Windows 11 25h2 | All | All | All | All |
| Operating System | Microsoft | Windows Server 2012 | - | All | All | All |
| Operating System | Microsoft | Windows Server 2012 | r2 | All | All | All |
| Operating System | Microsoft | Windows Server 2016 | All | All | All | All |
| Operating System | Microsoft | Windows Server 2019 | All | All | All | All |
| Operating System | Microsoft | Windows Server 2022 | All | All | All | All |
| Operating System | Microsoft | Windows Server 2022 23h2 | All | All | All | All |
| Operating System | Microsoft | Windows Server 2025 | All | All | All | All |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Microsoft | Windows 10 Version 1607 | affected 10.0.14393.0 10.0.14393.8783 custom | 32-bit Systems, x64-based Systems |
| CNA | Microsoft | Windows 10 Version 1809 | affected 10.0.17763.0 10.0.17763.8276 custom | 32-bit Systems, x64-based Systems |
| CNA | Microsoft | Windows 10 Version 21H2 | affected 10.0.19044.0 10.0.19044.6809 custom | 32-bit Systems, ARM64-based Systems, x64-based Systems |
| CNA | Microsoft | Windows 10 Version 22H2 | affected 10.0.19045.0 10.0.19045.6809 custom | 32-bit Systems, ARM64-based Systems, x64-based Systems |
| CNA | Microsoft | Windows 11 Version 23H2 | affected 10.0.22631.0 10.0.22631.6491 custom | ARM64-based Systems |
| CNA | Microsoft | Windows 11 Version 23H2 | affected 10.0.22631.0 10.0.22631.6491 custom | x64-based Systems |
| CNA | Microsoft | Windows 11 Version 24H2 | affected 10.0.26100.0 10.0.26100.7623 custom | ARM64-based Systems, x64-based Systems |
| CNA | Microsoft | Windows 11 Version 25H2 | affected 10.0.26200.0 10.0.26200.7623 custom | ARM64-based Systems, x64-based Systems |
| CNA | Microsoft | Windows Server 2012 | affected 6.2.9200.0 6.2.9200.25868 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2012 Server Core Installation | affected 6.2.9200.0 6.2.9200.25868 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2012 R2 | affected 6.3.9600.0 6.3.9600.22968 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2012 R2 Server Core Installation | affected 6.3.9600.0 6.3.9600.22968 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2016 | affected 10.0.14393.0 10.0.14393.8783 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2016 Server Core Installation | affected 10.0.14393.0 10.0.14393.8783 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2019 | affected 10.0.17763.0 10.0.17763.8276 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2019 Server Core Installation | affected 10.0.17763.0 10.0.17763.8276 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2022 | affected 10.0.20348.0 10.0.20348.4648 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2022 23H2 Edition Server Core Installation | affected 10.0.25398.0 10.0.25398.2092 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2025 | affected 10.0.26100.0 10.0.26100.32230 custom | x64-based Systems |
| CNA | Microsoft | Windows Server 2025 Server Core Installation | affected 10.0.26100.0 10.0.26100.32230 custom | x64-based Systems |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21265 | [email protected] | msrc.microsoft.com | Vendor Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.