VulnSocial

CVE-2026-21265Disclosure(microsoft / windows_10_1607)

LOWCVSS 6.4 · MEDIUM

Signal is active with 1 mentions in latest observed window

Immediate actions

  • Track advisory updates for patch or workaround availability

Recommended action window: Monitor and triage in normal cycle

NVD description

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.

microsoft CVEsBack to dashboard
0.5/ 10 priority

Sources & remediation

Vendor / third-party advisories
Weakness type (CWE)
CWE-1329

Priority

LOW

Exploitation

NONE

PoC

NONE

Patch

NONE

Momentum

NONE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

  • windows_10_1607
  • windows_10_1809
  • windows_10_21h2
  • windows_10_22h2

Threat summary

  • 1 mentions across 1 observed day

What's happening

  • Technical details provided in 1 signal
  • Disclosure: 1 classified signal
  • 1 total mentions across 1 day

Affected systems

Vendors
microsoft
Products
windows_10_1607windows_10_1809windows_10_21h2windows_10_22h2windows_11_23h2windows_11_24h2windows_11_25h2windows_server_2012windows_server_2016windows_server_2019

2 versions affected across 13 products

Deep dive

Activity timeline1 mentions / 1d
00111Mentions · 2026-01-30: 1Technical Details · 2026-01-30: 101-30
Signal classification1 categories
Disclosure
1100.0%
Full discourse1 post
  • m0n1@m0n1x90
    Disclosure

    CVE-2026-21265: Windows Secure Boot stores soon-to-expire Microsoft certs in UEFI KEK/DB. Failure to update risks boot security & loss of critical fixes. Firmware flaws may hinder updates, increasing attack potential. #Djin #CVE #CyberSecurity #Windows #UEFI #MSRC

    Post summary

    The tweet highlights CVE‑2026‑21265, noting that Windows Secure Boot stores soon‑to‑expire Microsoft certificates in UEFI KEK/DB, which poses boot‑security risks, but provides no proof of exploitation, patches, or active attacks.

    10000159
    659 followersView on X
CPE platform detail23 entries

23 of 23 entries

PartVendorProductVersionTarget SWTarget HW
OSmicrosoftwindows_10_1607--x64
OSmicrosoftwindows_10_1607--x86
OSmicrosoftwindows_10_1809--x64
OSmicrosoftwindows_10_1809--x86
OSmicrosoftwindows_10_21h2--arm64
OSmicrosoftwindows_10_21h2--x64
OSmicrosoftwindows_10_21h2--x86
OSmicrosoftwindows_10_22h2--arm64
OSmicrosoftwindows_10_22h2--x64
OSmicrosoftwindows_10_22h2--x86
OSmicrosoftwindows_11_23h2--arm64
OSmicrosoftwindows_11_23h2--x64
OSmicrosoftwindows_11_24h2--arm64
OSmicrosoftwindows_11_24h2--x64
OSmicrosoftwindows_11_25h2--arm64
OSmicrosoftwindows_11_25h2--x64
OSmicrosoftwindows_server_2012---
OSmicrosoftwindows_server_2012r2--
OSmicrosoftwindows_server_2016---
OSmicrosoftwindows_server_2019---
OSmicrosoftwindows_server_2022---
OSmicrosoftwindows_server_2022_23h2---
OSmicrosoftwindows_server_2025---

Explore more

Back to dashboardmicrosoft CVEswindows_10_1607 vulnerabilities