CVE-2025-21204 · Windows Process Activation Elevation of Privilege Vulnerability

Improper link resolution before file access ('link following') in Windows Update Stack allows an authorized attacker to elevate privileges locally.

Are the updates for Windows 10 for x64-based Systems and Windows 10 for 32-bit Systems currently available? Yes. As of April 9, 2025, the security update (5055547) for Windows 10 for x64-based Systems and Windows 10 for 32-bit Systems are available. Customers running Windows 10 should ensure the update is installed to be protected from this vulnerability.

How could an attacker exploit this vulnerability? An authenticated attacker who successfully exploits this vulnerability gains the ability to perform and/or manipulate file management operations on the victim machine in the context of the NT AUTHORITY\SYSTEM account.

Does installing the Windows security updates that address this CVE cause visible change on devices? After installing the updates listed in the Security Updates table for your operating system, a new %systemdrive%\inetpub folder will be created on your device. This folder should not be deleted regardless of whether Internet Information Services (IIS) is active on the target device. This behavior is part of changes that increase protection and does not require any action from IT admins and end users.

What remediation steps do I need to take to protect myself with regard to the %systemroot%\inetpub directory? For systems with KB5055528 installed and %systemroot%\inetpub directory intact, no additional action is required. For systems with KB5055528 installed but %systemroot%\inetpub directory deleted, immediate remediation is required. If the inetpub directory has been deleted, you need to run the remediation script Set-InetpubFolderAcl.ps1. This script will: Recreate the inetpub directory if it has been deleted. Ensure that the directory permissions are correctly configured to prevent unauthorized access and potential vulnerabilities related to CVE-2025-21204. Update ACLs for the DeviceHealthAttestation directory, if it exists. This directory was created on certain Server versions by the February 2025 security updates. The script will update the ACLs for the DeviceHealthAttestation directory to ensure it is secure.