CVE-2026-20842: Microsoft DWM Core Library Elevation of Privilege Vulnerability

Overview

Severity

High (CVSS 7)

CVSS Vector

CVSS:3.1/AV:L/AC:H/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

2026-Jan

Released

2026-01-13

EPSS Score

0.03% (percentile: 9.2%)

Description

Use after free in Windows DWM allows an authorized attacker to elevate privileges locally.

FAQ

According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability? For an attacker to exploit this vulnerability, they would need to have knowledge of a specific operation that triggers a memory allocation failure, specifically a use after free. What privileges could be gained by an attacker who successfully exploited this vulnerability? An attacker who successfully exploited this vulnerability could gain SYSTEM privileges.

Affected Products (17)

Windows

• Windows Server 2022
• Windows Server 2022 (Server Core installation)
• 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 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

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

Security Updates (6)

• 5073457
• 5073724
• 5073379
• 5074109
• 5073455
• 5073450

Acknowledgments

Varun Goel

Revision History

• 2026-01-13: Information published.