CVE detail
CVE-2026-21265
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.
Buzz score
Why this CVE is surfacing
This all-time snapshot uses the same composite formula as Trending across a 30-year evidence window, rather than a current rolling window.
Buzz score components · mention 16.1 · diversity 13.0 · KEV 0.0 · OTX 0.0 · PoC 0.0
Why it matters now
Mention timeline
- Total mentions
- 0
- within the 30d window
- Peak daily
- 0
- highest bucket
Evidence
Source links by recency
4 source links · newest first
- Microsoft Patch Tuesday security updates for January 2026 fixed actively exploited zero-daySecurity Affairs
Microsoft Patch Tuesday addressed 112 security flaws across Windows, Office, Azure, Edge, and more, including eight critical vulnerabilities, kicking off the new year with a major patch update. Microsoft Patch Tuesday security updates for January 2026 release 112 CVEs affecting Windows, Office, Azure, Edge, SharePoint, SQL Server, SMB, and Windows management services. Including third-party Chromium […]
newssecurityaffairs.comJan 14, 2026, 8:43 AM Eight critical vulnerabilities and an actively exploited zero day highlight Microsoft’s first Patch Tuesday announcements for 2026. Most of the higher scoring vulnerabilities impact Office products, with two holes in SharePoint scoring an 8.8 on the CVSS scale. “Last year’s abuse of SharePoint by Chinese APTs to deploy ToolShell against organizations should serve as a […]
newswww.csoonline.comJan 14, 2026, 1:50 AMTwo vulnerabilities patched this month by Microsoft were disclosed publicly before fixes were released.
newswww.securityweek.comJan 13, 2026, 9:00 PM- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21265msrc.microsoft.com
No excerpt available.
Vendor Advisorymsrc.microsoft.comJan 13, 2026, 6:16 PM
Exploit code
Public exploit repository references
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0 repository references · best confidence N/A · max 0 stars
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