CVE Watchtower

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CVE-2026-21265NVD

Vulnerability 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.
Severity Level
MEDIUM(6.4)
Published Date
Jan 13, 2026
Last Modified
Jul 30, 2026
Exploitation Status
ACTIVE
EPSS Score (30-Day)
1.00%Probability
Root Weakness (CWE)
Refer to the official MITRE database for detailed architectural specifications regarding this weakness.
CVSS v3.1 Base Metrics — Score 6.4 (MEDIUM)
Attack VectorLocal
Attack ComplexityHigh
Privileges RequiredHigh
User InteractionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

Affected & Patched Versions

Affected Versions
  • Microsoft Windows 10 1607 < 10.0.14393.8783
  • Microsoft Windows 10 1809 < 10.0.17763.8276
  • Microsoft Windows 10 21h2 < 10.0.19044.6809
  • Microsoft Windows 10 22h2 < 10.0.19045.6809
  • Microsoft Windows 11 23h2 < 10.0.22631.6491
  • Microsoft Windows 11 24h2 < 10.0.26100.7623
  • Microsoft Windows 11 25h2 < 10.0.26200.7623
  • Microsoft Windows Server 2012
  • Microsoft Windows Server 2016 < 10.0.14393.8783
  • Microsoft Windows Server 2019 < 10.0.17763.8276
  • Microsoft Windows Server 2022 < 10.0.20348.4648
  • Microsoft Windows Server 2022 23h2 < 10.0.25398.2092
  • Microsoft Windows Server 2025 < 10.0.26100.32230
Patched Versions
  • Microsoft Windows 10 1607 10.0.14393.8783
  • Microsoft Windows 10 1809 10.0.17763.8276
  • Microsoft Windows 10 21h2 10.0.19044.6809
  • Microsoft Windows 10 22h2 10.0.19045.6809
  • Microsoft Windows 11 23h2 10.0.22631.6491
  • Microsoft Windows 11 24h2 10.0.26100.7623
  • Microsoft Windows 11 25h2 10.0.26200.7623
  • Microsoft Windows Server 2016 10.0.14393.8783
  • Microsoft Windows Server 2019 10.0.17763.8276
  • Microsoft Windows Server 2022 10.0.20348.4648
  • Microsoft Windows Server 2022 23h2 10.0.25398.2092
  • Microsoft Windows Server 2025 10.0.26100.32230
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🎁7-Day Free Trial — Try Pro or Team, no card required.
📧Email Delivery — Threat intel straight to your inbox.
♾️Unlimited Vendors — Track your entire stack.
🚨All New CVEs — Be the first to know.
📈EPSS Spike Alerts — Catch rising risk before it peaks.
🎯Custom EPSS/CVSS — Filter noise, focus on risk.
🛡️Exploit Intel — A 2nd confirmed-exploit signal beyond KEV.
🐙GitHub Issues — Auto-tracked, no duplicates.
📬Weekly Digest — One clean summary, not inbox spam.
🏷️Watchlist Groups — Tag alerts by team (Infra/AppSec/SOC).
💬Webhooks — Slack & Teams integration.
🔀Smart Routing — Critical alerts to one channel, rest to another.
🚫Ad-Free — Uninterrupted experience.