Weak Authentication in Microsoft Windows and Windows Server - CVE-2026-85939
Published: October 14, 2026
Vulnerability identifier: #VU155252
CSH Severity: Low
CVSS v4: 6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-85939
CWE-ID: CWE-1390
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to bypass a security feature.
The vulnerability exists due to weak authentication in Windows Kernel when handling authentication over a network. A remote user can exploit the authentication weakness to bypass a security feature.
Exploitation depends on a target environment configuration that could occur accidentally.
Affected software
Microsoft Windows
Windows Server
Windows Server
How to mitigate CVE-2026-85939
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