CVE-2021-25195: Windows PKU2U Elevation of Privilege 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
Elevation of Privilege
Exploit Status
Not Exploited
Exploitation Likelihood
Less Likely
Patch Tuesday
2021-Feb
Released
2021-02-09
EPSS Score
0.19% (percentile: 41.3%)

FAQ

What is PKU2U? PKU2U is a peer-to-peer authentication protocol. This setting prevents online identities from authenticating to domain-joined systems. Authentication will be centrally managed with Windows user accounts. How do I know if my servers are exploitable by this vulnerability? If your servers are not configured to allow the use of PKU2U authentication, they would not be vulnerable. In all cases, Microsoft strongly recommends that you install the updates for this vulnerability as soon as possible even if you do not use PKU2U authentication. Please see Network security Allow PKU2U authentication requests to this computer to use online identities for more information.

Affected Products (36)

Windows

  • Windows 10 Version 20H2 for 32-bit Systems
  • Windows 10 Version 20H2 for ARM64-based Systems
  • Windows Server, version 20H2 (Server Core Installation)
  • Windows 10 Version 1803 for 32-bit Systems
  • Windows 10 Version 1803 for x64-based Systems
  • Windows 10 Version 1803 for ARM64-based Systems
  • Windows 10 Version 1809 for 32-bit Systems
  • Windows 10 Version 1809 for x64-based Systems
  • Windows 10 Version 1809 for ARM64-based Systems
  • Windows Server 2019
  • Windows Server 2019 (Server Core installation)
  • Windows 10 Version 1909 for 32-bit Systems
  • Windows 10 Version 1909 for x64-based Systems
  • Windows 10 Version 1909 for ARM64-based Systems
  • Windows Server, version 1909 (Server Core installation)
  • Windows 10 Version 2004 for 32-bit Systems
  • Windows 10 Version 2004 for ARM64-based Systems
  • Windows 10 Version 2004 for x64-based Systems
  • Windows Server, version 2004 (Server Core installation)
  • Windows 10 for 32-bit Systems
  • Windows 10 for x64-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)
  • Windows 8.1 for 32-bit systems
  • Windows 8.1 for x64-based systems
  • Windows RT 8.1

ESU

  • Windows 7 for 32-bit Systems Service Pack 1
  • Windows 7 for x64-based Systems Service Pack 1
  • Windows Server 2008 R2 for x64-based Systems Service Pack 1
  • Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)
  • Windows Server 2012
  • Windows Server 2012 (Server Core installation)
  • Windows Server 2012 R2
  • Windows Server 2012 R2 (Server Core installation)

Security Updates (12)

Acknowledgments

Maxwell Whitaker of Microsoft’s Security Assurance and Vulnerability Research team

Revision History

  • 2021-02-09: Information published.