CVE-2026-20838: Windows Kernel Information Disclosure Vulnerability

Overview

Severity

Medium (CVSS 5.5)

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/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

Less Likely

Patch Tuesday

2026-Jan

Released

2026-01-13

EPSS Score

0.06% (percentile: 17.3%)

Description

Generation of error message containing sensitive information in Windows Kernel allows an authorized 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 (11)

Windows

• Windows Server 2022
• Windows Server 2022 (Server Core installation)
• Windows Server 2025 (Server Core installation)
• Windows 11 Version 25H2 for ARM64-based Systems
• Windows 11 Version 25H2 for x64-based Systems
• Windows 11 Version 23H2 for ARM64-based Systems
• Windows 11 Version 23H2 for x64-based Systems
• Windows Server 2022, 23H2 Edition (Server Core installation)
• Windows 11 Version 24H2 for ARM64-based Systems
• Windows 11 Version 24H2 for x64-based Systems
• Windows Server 2025

Security Updates (5)

• 5073457
• 5073379
• 5074109
• 5073455
• 5073450

Acknowledgments

Microsoft Offensive Research & Security Engineering

Revision History

• 2026-01-13: Information published.