CVE-2026-20818: Windows Kernel Information Disclosure Vulnerability

Overview

Severity

Medium (CVSS 6.2)

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C

Category

Information Disclosure

Exploit Status

Not Exploited

Exploitation Likelihood

Unlikely

Patch Tuesday

2026-Jan

Released

2026-01-13

Last Updated

2026-01-20

EPSS Score

0.04% (percentile: 12.4%)

Description

Insertion of sensitive information into log file in Windows Kernel allows an unauthorized attacker to disclose information locally.

FAQ

What type of information could be disclosed by this vulnerability? The type of information that could be disclosed if an attacker successfully exploited this vulnerability is Kernel memory read - unintentional read access to memory contents in kernel space from a user mode process.

Affected Products (9)

Windows

• Windows Server 2019
• Windows Server 2019 (Server Core installation)
• Windows Server 2022
• Windows Server 2022 (Server Core installation)
• Windows Server 2025 (Server Core installation)
• Windows Server 2022, 23H2 Edition (Server Core installation)
• Windows Server 2025
• Windows Server 2016
• Windows Server 2016 (Server Core installation)

Security Updates (5)

• 5073723
• 5073457
• 5073379
• 5073450
• 5073722

Acknowledgments

Microsoft Offensive Research & Security Engineering

Revision History

• 2026-01-13: Information published.
• 2026-01-20: Updated the build numbers. This is an informational update only.