Reliance on Untrusted Inputs in a Security Decision in Windows and Windows Server - CVE-2026-20849
Published: January 13, 2026
Vulnerability identifier: #VU121322
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-2026-20849
CWE-ID: CWE-807
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Microsoft
Affected software:
Windows
Windows Server
Windows
Windows Server
Detailed vulnerability description
The vulnerability allows a remote user to escalate privileges on the system.
The vulnerability exists due to reliance on untrusted input for a security decision in Windows Kerberos, which leads to security restrictions bypass and privilege escalation.
How to mitigate CVE-2026-20849
Install updates from vendor's website.