Path traversal in Windows and Windows Server - CVE-2026-40400
Published: July 17, 2026
Vulnerability identifier: #VU137956
CSH Severity: High
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber
CVE-ID: CVE-2026-40400
CWE-ID: CWE-22
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 attacker to execute arbitrary code.
The vulnerability exists due to path traversal in Windows PowerShell when processing a crafted link path over the network. A remote attacker can cause an authenticated client to click a crafted link to execute arbitrary code.
User interaction is required, and exploitation depends on an authenticated client clicking a link.
How to mitigate CVE-2026-40400
Install security update from vendor's website.