Heap-based buffer overflow in Microsoft Windows and Windows Server - CVE-2026-100203
Published: October 13, 2026
Vulnerability identifier: #VU154231
CSH Severity: Low
CVSS v4: 7.3 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-100203
CWE-ID: CWE-122
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 a heap-based buffer overflow in Windows Update Service when exploited locally. A local user can exploit the buffer overflow to escalate privileges to SYSTEM.
Successful exploitation requires specific conditions, such as particular protocol settings or configurations. The advisory does not identify the exact conditions required.
Affected software
Microsoft Windows
Windows Server
Windows Server
How to mitigate CVE-2026-100203
Install security update from vendor's website.
Microsoft Windows - addressed in versions 10 21H2 10.0.19044.7807, 10 1607 10.0.14393.9612, 10 1809 10.0.17763.9376, 11 23H2 10.0.22631.7652, 11 24H2 10.0.26100.9711, 11 25H2 10.0.26200.9711, 11 26H1 10.0.28000.3231
Windows Server - addressed in versions 2016 10.0.14393.9612, 2019 10.0.17763.9376, 2022 10.0.20348.5761, 2025 10.0.26100.33650
Windows Server - addressed in versions 2016 10.0.14393.9612, 2019 10.0.17763.9376, 2022 10.0.20348.5761, 2025 10.0.26100.33650