Use-after-free in Windows Server and Windows - CVE-2026-20854
Published: January 13, 2026
Vulnerability identifier: #VU121259
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-20854
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Microsoft
Affected software:
Windows Server
Windows
Windows Server
Windows
Detailed vulnerability description
The vulnerability allows a remote attacker to compromise vulnerable system.
The vulnerability exists due to a use-after-free error in Windows Local Security Authority Subsystem Service (LSASS). A remote user can execute arbitrary code on the target system.
How to mitigate CVE-2026-20854
Install updates from vendor's website.