Vulnerability in Microsoft Windows 10 1607 (CVE-2026-21265)
Summary
Vulnerability in Microsoft Windows 10 1607 (CVE-2026-21265). Successful exploitation can lead to full system takeover.
Original description
The description as published by the source.
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: NIST National Vulnerability Database NVD
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-21265 has been found in Microsoft Windows 10 1607.
Successful exploitation can lead to full system takeover. CVSS score: 6.4/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Microsoft Windows 10 1607 CVE-2026-21265" on the vendor's site.
CVE-2026-21265 (Microsoft Windows 10 1607) — CWE-1329 / CVSS v3 6.4
Attack vector: local / no user interaction
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-1329) exists in Microsoft Windows 10 1607.
Check the vendor advisory for the affected versions of Microsoft Windows 10 1607.
Severity: Medium (CVSS 6.4/10). Successful exploitation can lead to full system takeover.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Microsoft Windows 10 1607 を使っているサービスとバージョンを洗い出す。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
References
- patch secure@microsoft.com