CVE-2026-8863: UEFI Secure Boot Security Feature Bypass Vulnerability

Overview

Severity
High (CVSS 7.8)
CVSS Vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Category
Security Feature Bypass
Exploit Status
Not Exploited
Exploitation Likelihood
Less Likely
Patch Tuesday
2026-Jun
Released
2026-06-09

Description

Protection mechanism failure in Windows UEFI allows an authorized attacker to bypass a security feature locally.

FAQ

What kind of security feature could be bypassed by successfully exploiting this vulnerability? Successfully exploiting this vulnerability could bypass UEFI Secure Boot, a security feature designed to ensure that only trusted software runs when a device starts. This could allow an attacker with local administrator privileges or physical access to run untrusted code early in the boot process, before the operating system’s protections are active.

Affected Products (30)

Windows

  • Windows Server 2019
  • Windows Server 2022
  • Windows Server 2022 (Server Core installation)
  • Windows Server 2019 (Server Core installation)
  • 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 11 Version 25H2 for ARM64-based Systems
  • Windows Server 2025 (Server Core installation)
  • Windows 11 Version 25H2 for x64-based Systems
  • Windows 11 Version 23H2 for x64-based Systems
  • Windows 11 Version 23H2 for ARM64-based Systems
  • Windows 11 Version 24H2 for ARM64-based Systems
  • Windows 11 Version 24H2 for x64-based Systems
  • Windows 11 version 26H1 for x64-based Systems
  • Windows Server 2025
  • Windows 11 Version 26H1 for ARM64-based Systems
  • Windows 10 Version 1607 for 32-bit Systems
  • Windows 10 Version 1607 for x64-based Systems
  • Windows Server 2016
  • Windows Server 2016 (Server Core installation)

ESU

  • Windows 10 Version 22H2 for x64-based Systems
  • Windows 10 Version 22H2 for ARM64-based Systems
  • Windows 10 Version 22H2 for 32-bit Systems
  • Windows Server 2012 (Server Core installation)
  • Windows Server 2012
  • Windows Server 2012 R2
  • Windows Server 2012 R2 (Server Core installation)

Security Updates (10)

Acknowledgments

Martin Smolar ESET , Martin Smolar ESET

Revision History

  • 2026-06-09: Information published.