External Control of File Name or Path in Windows and Windows Server - CVE-2026-20931
Published: January 14, 2026
Vulnerability identifier: #VU121445
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:A/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-20931
CWE-ID: CWE-73
Exploitation vector: Adjecent network
Exploit availability:
No public exploit available
Vendor: Microsoft
Affected software:
Windows
Windows Server
Windows
Windows Server
Detailed vulnerability description
The vulnerability allows a remote attacker to compromise the target system.
The vulnerability exists due to external control of file name or path in Windows Telephony Service. A remote user on the local network can gain elevated privileges on the system.
How to mitigate CVE-2026-20931
Install updates from vendor's website.