Local Privilege Escalation Risk in Windows Cloud Files Mini Filter Driver

Historical catalog analysis: CISA added this entry on December 09, 2025. The entry reflects catalog information retrieved on August 31, 2026, not a snapshot archived on the inclusion date. Check current vendor guidance before acting.

What the vulnerability is

CVE-2025-62221 is a Use After Free (CWE-416) vulnerability located within the Cloud Files Mini Filter Driver of Microsoft Windows. This specific flaw allows an attacker who already has authorized access to a system to elevate their privileges locally. In a healthcare environment, local privilege escalation is a critical stage in an attack chain, as it can allow a user with limited permissions to gain administrative control over a workstation or server.

Exposure and applicability

This vulnerability applies to Microsoft Windows environments utilizing the Cloud Files Mini Filter Driver. For U.S. healthcare providers and business associates, this is highly relevant given the ubiquity of Windows across clinical workstations, medical imaging servers, and administrative systems that process electronic Protected Health Information (ePHI).

Because this is a local privilege escalation flaw, it does not provide an initial entry point into the network. Instead, it targets systems where an attacker has already established a foothold—such as through compromised user credentials or a separate initial access vector—and seeks to bypass security boundaries to access restricted patient data or deploy system-wide malware.

Remediation priorities

Our analysis suggests that healthcare security leaders prioritize the following actions based on the risk to patient data continuity and confidentiality:

1. Patch Deployment: Prioritize the application of vendor-supplied updates for Microsoft Windows across all endpoints. Systems with direct access to ePHI databases or those used by high-privilege clinical staff should be prioritized.
2. Principle of Least Privilege (PoLP): Review and restrict local administrative rights. Since this vulnerability requires an authorized attacker, reducing the number of users with initial access to sensitive systems could reduce the potential attack surface.
3. Endpoint Hardening: Ensure that security configurations are aligned with vendor guidance to limit the ability of unauthorized processes to interact with kernel-level drivers.

How to validate remediation

To verify that exposure has been reduced, organizations should employ the following methods:

• Version Verification: Confirm through centralized patch management systems that the specific updates addressing CVE-2025-62221 have been successfully installed across the fleet.
• Configuration Audit: Review system logs and configuration baselines to ensure that unauthorized privilege changes are being monitored and alerted upon.

Note: Version checks alone do not guarantee total security, but they provide evidence that the known flaw has been addressed via the vendor’s provided fix.

Limits and open questions

It remains unknown whether this vulnerability is currently being leveraged by active ransomware campaigns. Additionally, while CISA has established a remediation deadline of December 30, 2025, for federal agencies, this date serves as a risk benchmark rather than a legal requirement for private healthcare entities.

Residual risk persists if legacy systems cannot be patched due to vendor dependencies (e.g., older medical device software). In such cases, the vulnerability may remain present, necessitating compensating controls such as strict network segmentation to isolate those devices from the broader clinical network.

Source and editorial note

CVE-2025-62221: Microsoft Windows Use After Free Vulnerability · Source date: December 09, 2025 · Retrieved August 31, 2026.

Material facts are tied to the cited primary source. Recommendations are independent defensive analysis unless attributed to the source. Confirm consequential decisions against current authoritative guidance.

Archive date: December 12, 2025. The displayed post date is assigned three days after the source date to organize this retrospective archive; it does not mean this site published the analysis then. First published by this site: September 24, 2026 at 00:51 UTC.

Request a healthcare security assessment