Use-after-free in Microsoft Windows and Windows Server - CVE-2026-20870
Published: January 14, 2026
Vulnerability identifier: #VU121417
CSH Severity: Low
CVSS v4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-20870
CWE-ID: CWE-416
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to compromise vulnerable system.
The vulnerability exists due to a use-after-free error in Windows Win32 Kernel Subsystem. A local user can gain elevated privileges on the target system.
Affected software
Microsoft Windows
Windows Server
Windows Server
How to mitigate CVE-2026-20870
Install updates from vendor's website.
Microsoft Windows - addressed in versions 11 24H2 10.0.26100.3223, 11 24H2 10.0.26100.7623
Windows Server - addressed in versions 2025 10.0.26100.7623, 2025 10.0.26100.32230
Windows Server - addressed in versions 2025 10.0.26100.7623, 2025 10.0.26100.32230