CVE-2026-105009: Windows Server Update Service Elevation of Privilege Vulnerability

Overview

Severity

High (CVSS 7.5)

CVSS Vector

CVSS:3.1/AV:L/AC:H/PR:L/UI:R/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-Oct

Released

2026-10-13

Description

Incorrect default permissions in Windows Server Update Service allows an authorized attacker to elevate privileges locally.

FAQ

What privileges could be gained by an attacker who successfully exploited this vulnerability? An attacker who successfully exploited this vulnerability could gain SYSTEM privileges. 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 and also to take additional actions prior to exploitation to prepare the target environment.

Affected Products (12)

ESU

• Windows Server 2012
• Windows Server 2012 (Server Core installation)
• Windows Server 2012 R2
• Windows Server 2012 R2 (Server Core installation)

Windows

• Windows Server 2016
• Windows Server 2016 (Server Core installation)
• Windows Server 2019
• Windows Server 2019 (Server Core installation)
• Windows Server 2022
• Windows Server 2022 (Server Core installation)
• Windows Server 2025
• Windows Server 2025 (Server Core installation)

Security Updates (6)

• 5126835
• 5126836
• 5126868
• 5126651
• 5126655
• 5126646

Acknowledgments

yhw

Revision History

• 2026-10-13: Information published.