Windows Cloud Files Mini Filter Driver 0-Day Actively Exploited for Privilege Escalation

Microsoft has disclosed a critical elevation-of-privilege vulnerability in the Windows Cloud Files Mini Filter Driver that could allow local attackers to gain system-level access on vulnerable machines.

The vulnerability, tracked as CVE-2025-62221 and released on December 9, 2025, represents a significant security threat to Windows environments worldwide.

Field	Value
CVE ID	CVE-2025-62221
Vulnerability Type	Elevation of Privilege
Release Date	December 9, 2025
CVSS Score	7.8 / 6.8
Severity Rating	Important
Attack Vector	Local
Attack Complexity	Low
Privileges Required	Low
User Interaction	None

Technical Details of the Vulnerability

The vulnerability stems from a use-after-free condition in the Cloud Files Mini Filter Driver, a core Windows component that manages cloud storage integration.

This memory safety issue, classified as CWE-416, can lead to arbitrary code execution and complete system compromise.

Attackers with local access can exploit this flaw to escalate privileges from standard user accounts to administrator or system-level access without requiring any user interaction.

The CVSS v3.1 base score of 7.8 and environmental score of 6.8 reflect the severity of this threat.

The vulnerability vector string (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C) indicates a local attack vector and low attack complexity, with minimal privilege requirements, making exploitation accessible to many potential attackers.

The vulnerability is currently classified as confirmed, suggesting that proof-of-concept code or active exploitation may already exist in the wild.

This status elevates the urgency for organizations to implement protective measures immediately. The ease of exploitation combined with the potential for complete system compromise makes this a high-priority threat for enterprise environments.

Organizations should prioritize patching this vulnerability across their Windows environments as security updates become available from Microsoft.

Until patches are deployed, administrators should review access controls and monitor systems for suspicious privilege escalation activities.

Security teams should implement enhanced logging and monitoring to detect potential exploitation attempts.

Given that the Cloud Files Mini Filter Driver is integral to Windows’ cloud storage functionality, disabling it may impact system features.

Therefore, timely patching is essential rather than attempting workarounds.

This disclosure underscores the critical importance of applying current security patches and implementing the principle of least privilege across enterprise infrastructure to minimize exposure to privilege-escalation attacks.

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