Incorrect default permissions in Windows Server - CVE-2026-105009
Published: October 13, 2026
Vulnerability identifier: #VU154327
CSH Severity: Medium
CVSS v4: 7.1 [CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-105009
CWE-ID: CWE-276
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to escalate privileges to SYSTEM.
The vulnerability exists due to incorrect default permissions in Windows Server Update Service when accessed locally. A local user can exploit these permissions by winning a race condition to escalate privileges to SYSTEM.
Successful exploitation requires additional actions beforehand to prepare the target environment. User interaction is required.
Affected software
Windows Server
How to mitigate CVE-2026-105009
Install security update from vendor's website.
Windows Server - addressed in versions 2012 R2 6.3.9600.23470, 2012 6.2.9200.26434, 2016 10.0.14393.9612, 2019 10.0.17763.9376, 2022 10.0.20348.5761, 2025 10.0.26100.33650