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Δ / VULNERABILITY RECORD

CVE-2026-21265.

Source-reported disclosure and enrichment record.

SEVERITY / CVSSMEDIUM / 6.4No severity score in this snapshot.
EXPLOITATION STATUSNot listed in the cached KEV catalogThis does not establish absence of exploitation.
RECORD STATUSMicrosoft vendor recordModified Jan 13, 2026

Disclosure 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.

Source-reported weakness categories

CWE-1329

Source-specific records & product guidance

Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.

Microsoft Security Updates (CVRF) · 2026-Jan

Open original source · Updated Jan 13, 2026

Secure Boot Certificate Expiration Security Feature Bypass Vulnerability

Maximum of vendor-reported product scores; products and fixed builds are associations, not a universal affected-version statement.

Microsoft maximum product score: 6.4

VendorProduct / associationVersion / bounds
Microsoft update guideWindows 10 Version 1809 for 32-bit Systems (MSRC status code 3)
Microsoft update guideWindows 10 Version 1809 for x64-based Systems (MSRC status code 3)
Microsoft update guideWindows Server 2019 (MSRC status code 3)
Microsoft update guideWindows Server 2019 (Server Core installation) (MSRC status code 3)
Microsoft update guideWindows Server 2022 (MSRC status code 3)
Microsoft update guideWindows Server 2022 (Server Core installation) (MSRC status code 3)
Microsoft update guideWindows 10 Version 21H2 for 32-bit Systems (MSRC status code 3)
Microsoft update guideWindows 10 Version 21H2 for ARM64-based Systems (MSRC status code 3)
Microsoft update guideWindows 10 Version 21H2 for x64-based Systems (MSRC status code 3)
Microsoft update guideWindows 10 Version 22H2 for x64-based Systems (MSRC status code 3)
Microsoft update guideWindows 10 Version 22H2 for ARM64-based Systems (MSRC status code 3)
Microsoft update guideWindows 10 Version 22H2 for 32-bit Systems (MSRC status code 3)
Microsoft update guideWindows Server 2025 (Server Core installation) (MSRC status code 3)
Microsoft update guideWindows 11 Version 25H2 for ARM64-based Systems (MSRC status code 3)
Microsoft update guideWindows 11 Version 25H2 for x64-based Systems (MSRC status code 3)
Microsoft update guideWindows 11 Version 23H2 for ARM64-based Systems (MSRC status code 3)
Microsoft update guideWindows 11 Version 23H2 for x64-based Systems (MSRC status code 3)
Microsoft update guideWindows Server 2022, 23H2 Edition (Server Core installation) (MSRC status code 3)
Microsoft update guideWindows 11 Version 24H2 for ARM64-based Systems (MSRC status code 3)
Microsoft update guideWindows 11 Version 24H2 for x64-based Systems (MSRC status code 3)
Microsoft update guideWindows Server 2025 (MSRC status code 3)
Microsoft update guideWindows 10 Version 1607 for 32-bit Systems (MSRC status code 3)
Microsoft update guideWindows 10 Version 1607 for x64-based Systems (MSRC status code 3)
Microsoft update guideWindows Server 2016 (MSRC status code 3)
Microsoft update guideWindows Server 2016 (Server Core installation) (MSRC status code 3)
Microsoft update guideWindows Server 2012 (MSRC status code 3)
Microsoft update guideWindows Server 2012 (Server Core installation) (MSRC status code 3)
Microsoft update guideWindows Server 2012 R2 (MSRC status code 3)
Microsoft update guideWindows Server 2012 R2 (Server Core installation) (MSRC status code 3)

Vendor remediation references

  • 5073723 · build 10.0.17763.8276 · product IDs 11568, 11569, 11571, 11572
  • Vendor guidance · product IDs 11568, 11569, 11571, 11572
  • 5073723 · product IDs 11568, 11569, 11571, 11572
  • 5073457 · build 10.0.20348.4648 · product IDs 11923, 11924
  • Vendor guidance · product IDs 11923, 11924
  • 5073457 · product IDs 11923, 11924
  • 5073724 · build 10.0.19044.6809 · product IDs 11929, 11930, 11931
  • Vendor guidance · product IDs 11929, 11930, 11931
  • 5073724 · product IDs 11929, 11930, 11931, 12097, 12098, 12099
  • 5073724 · build 10.0.19045.6809 · product IDs 12097, 12098, 12099
  • Vendor guidance · product IDs 12097, 12098, 12099
  • 5073379 · build 10.0.26100.32230 · product IDs 12437, 12436
  • Vendor guidance · product IDs 12437, 12436
  • 5073379 · product IDs 12437, 12436
  • 5074109 · build 10.0.26200.7623 · product IDs 20437, 20438
  • Vendor guidance · product IDs 20437, 20438
  • 5074109 · product IDs 20437, 20438, 12389, 12390
  • 5073455 · build 10.0.22631.6491 · product IDs 12242, 12243
  • Vendor guidance · product IDs 12242, 12243
  • 5073455 · product IDs 12242, 12243
  • 5073450 · build 10.0.25398.2092 · product IDs 12244
  • Vendor guidance · product IDs 12244
  • 5073450 · product IDs 12244
  • 5074109 · build 10.0.26100.7623 · product IDs 12389, 12390
  • Vendor guidance · product IDs 12389, 12390
  • 5073722 · build 10.0.14393.8783 · product IDs 10852, 10853, 10816, 10855
  • Vendor guidance · product IDs 10852, 10853, 10816, 10855
  • 5073698 · build 6.2.9200.25868 · product IDs 10378, 10379
  • Vendor guidance · product IDs 10378, 10379
  • 5073696 · build 6.3.9600.22968 · product IDs 10483, 10543
  • Vendor guidance · product IDs 10483, 10543

Original records & references

PUBLISHED 2026-01-13T03:00:00-05:00
MODIFIED 2026-01-13T03:00:00-05:00
INGESTED 2026-10-08T12:45:23-04:00