CVE-2026-20877: Windows Management Services Elevation of Privilege Vulnerability

Overview

Severity

High (CVSS 7.8)

CVSS Vector

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/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: 6.8%)

Description

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

FAQ

According to the CVSS metric, successful exploitation could lead to a scope change (S:C). What does this mean for this vulnerability? In this case, a successful attack could be performed from a low privilege AppContainer. The attacker could elevate their privileges and execute code or access resources at a higher integrity level than that of the AppContainer execution environment. According to the CVSS metric, the attack complexity is high (AC:H). What does that mean for this vulnerability? Successful exploitation of this vulnerability requires an attacker to win a race condition. What privileges could be gained by an attacker who successfully exploited the vulnerability? An attacker could use this vulnerability to elevate privileges from a Low Integrity Level in a contained ("sandboxed") execution environment to a Medium Integrity Level. Please refer to AppContainer isolation and Mandatory Integrity Control for more information.

Affected Products (21)

Windows

• Windows 10 Version 1809 for 32-bit Systems
• Windows 10 Version 1809 for x64-based Systems
• Windows Server 2019
• Windows Server 2019 (Server Core installation)
• 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 (7)

• 5073723
• 5073457
• 5073724
• 5073379
• 5074109
• 5073455
• 5073450

Acknowledgments

Anonymous

Revision History

• 2026-01-13: Information published.