CVE-2026-21265HighMicrosoft CVSS 6.4CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Microsoft security update for CVE-2026-21265 — Windows

Published
June 2, 2026
Last Modified
—

🔗 CVE IDs covered (1)

CVE-2026-21265 →

📋 Microsoft's advisory

EchelonGraph does not copy Microsoft's advisory page: its FAQ and remediation text are not shown here. Read the advisory on https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21265. This page also shows what EchelonGraph holds for CVE-2026-21265, with the description from its CVE record, which the CVE Numbering Authority that assigned the CVE wrote: for a CVE Microsoft assigned, often in the words of Microsoft's own advisory.

🎯 Affected products29

  • Windows 10 Version 1607 for 32-bit Systems
  • Windows 10 Version 1607 for x64-based Systems
  • Windows 10 Version 1809 for 32-bit Systems
  • Windows 10 Version 1809 for x64-based Systems
  • Windows 10 Version 21H2 for 32-bit Systems
  • Windows 10 Version 21H2 for ARM64-based Systems
  • Windows 10 Version 21H2 for x64-based Systems
  • Windows 10 Version 22H2 for 32-bit Systems
  • Windows 10 Version 22H2 for ARM64-based Systems
  • Windows 10 Version 22H2 for x64-based Systems
  • Windows 11 Version 23H2 for ARM64-based Systems
  • Windows 11 Version 23H2 for x64-based Systems
  • Windows 11 Version 24H2 for ARM64-based Systems
  • Windows 11 Version 24H2 for x64-based Systems
  • Windows 11 Version 25H2 for ARM64-based Systems
  • Windows 11 Version 25H2 for x64-based Systems
  • Windows Server 2012
  • Windows Server 2012 (Server Core installation)
  • Windows Server 2012 R2
  • Windows Server 2012 R2 (Server Core installation)
  • Windows Server 2016
  • Windows Server 2016 (Server Core installation)
  • Windows Server 2019
  • Windows Server 2019 (Server Core installation)
  • Windows Server 2022
  • Windows Server 2022 (Server Core installation)
  • Windows Server 2022, 23H2 Edition (Server Core installation)
  • Windows Server 2025
  • Windows Server 2025 (Server Core installation)

✅ Updates Microsoft lists: 10 KB articles

12 rows: one per KB article or update, update type and fixed build. Their details are on Microsoft's advisory.

KB articleUpdateFixed build
KB5073723Security Update10.0.17763.8276
KB5073457Security Update10.0.20348.4648
KB5073724Security Update10.0.19044.6809
KB5073724Security Update10.0.19045.6809
KB5073379Security Update10.0.26100.32230
KB5074109Security Update10.0.26200.7623
KB5073455Security Update10.0.22631.6491
KB5073450Security Update10.0.25398.2092
KB5074109Security Update10.0.26100.7623
KB5073722Security Update10.0.14393.8783
KB5073698Monthly Rollup6.2.9200.25868
KB5073696Monthly Rollup6.3.9600.22968

🧭 EchelonGraph on CVE-2026-21265

EchelonGraph score
6.4 MEDIUM
CISA KEV
Not listed
Fix status
A fix is available — apply it.

Description from the CVE record (CVE.org), as published by its numbering authority

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.

Published by Microsoft Corporation, the CVE Numbering Authority that assigned CVE-2026-21265, in its CVE record at CVE.org; reused under the CVE Program's Terms of Use (its licence and MITRE's copyright notice are in our Terms of Service).

🔗 References (22)