Use After Free in Windows Cloud Files Mini Filter Driver

Executive Summary

CVE-2026-50374 is a use-after-free vulnerability in the Windows Cloud Files Mini Filter Driver. This type of vulnerability occurs when a program continues to use memory after it has been freed, which can lead to unexpected behavior or exploitation.

In this case, an authorized attacker with physical access to the system can exploit this flaw to elevate their privileges. This means the attacker could gain higher-level permissions on the system, potentially allowing them to perform actions they would not normally be able to do.

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Detection Guidance

This vulnerability requires physical access to exploit, so detection focuses on monitoring for unusual privilege escalation attempts or suspicious activity in the Windows Cloud Files Mini Filter Driver. Check Windows Event Logs for events related to the driver or privilege changes. Use commands like 'fltmc' to list mini-filter drivers and verify the Cloud Files Mini Filter Driver is running.

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Impact Analysis

If you are affected by this vulnerability, an attacker with physical access to your system and some level of authorization could exploit it to elevate their privileges.

• The attacker could gain higher-level access to your system, potentially allowing them to execute arbitrary code or commands with elevated permissions.
• This could lead to unauthorized access to sensitive data, installation of malware, or other malicious activities that compromise the security and integrity of your system.

The CVSS base score of 6.3 indicates a medium severity, but the requirement for physical access and some level of authorization limits the scope of potential attacks.

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Compliance Impact

This vulnerability could impact compliance with standards and regulations that require protection of sensitive data and system integrity.

• GDPR: If the vulnerability leads to unauthorized access to personal data, it could result in a data breach, violating GDPR requirements for data protection and potentially leading to fines or legal consequences.
• HIPAA: For organizations handling protected health information (PHI), exploitation of this vulnerability could lead to unauthorized access to PHI, violating HIPAA's security and privacy rules.
• Other standards like ISO 27001 or NIST frameworks may also be affected, as they require maintaining the confidentiality, integrity, and availability of information systems.

To maintain compliance, organizations should apply the necessary patches or mitigations provided by Microsoft to address this vulnerability.

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Mitigation Strategies

Apply the security update provided by Microsoft to address CVE-2026-50374. The update can be found in the Microsoft Update Guide for this vulnerability.

• Ensure all systems running the affected Windows Cloud Files Mini Filter Driver are updated to the latest patched version.
• Restrict physical access to systems to prevent potential exploitation by an authorized attacker with physical access.

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