A critical privilege escalation vulnerability in Microsoft Windows Cloud Files Mini Filter Driver is now under active exploitation, according to a new Cybersecurity and Infrastructure Security Agency (CISA) advisory.
The vulnerability, tracked as CVE-2025-62221, poses a significant risk to Windows systems and has prompted urgent security recommendations.
The use-after-free vulnerability allows authorized attackers to escalate their privileges locally on affected Windows systems.
This type of flaw enables attackers who have initial access to a system to gain elevated permissions, potentially leading to complete system compromise.
The vulnerability affects the Windows Cloud Files Mini Filter Driver component, which manages file synchronization and cloud storage operations across the operating system.
CISA added CVE-2025-62221 to its Known Exploited Vulnerabilities Catalog on December 9, 2025, confirming active exploitation in the wild. Organizations have until December 30, 2025, to implement patches and mitigations.
The vulnerability is associated with CWE-416, a weakness category for use-after-free memory vulnerabilities that can be exploited to execute arbitrary code or gain unauthorized access.
Microsoft has released security updates to address this vulnerability, and organizations should prioritize applying these patches immediately.
The vulnerability particularly affects cloud service environments, making it essential for organizations that rely on cloud-based file synchronization to address this issue urgently.
For organizations unable to deploy patches immediately, CISA recommends implementing compensating controls and following the guidance in Executive Order 14028 and BOD 22-01 directives.
These mitigations may include network segmentation, enhanced monitoring of system access, and restricting user privileges to the minimum necessary levels.
If adequate mitigations cannot be implemented, discontinuing use of the affected component is recommended.
Security teams should review their Windows deployments, identify systems running vulnerable versions of the Cloud Files Mini Filter Driver, and prioritize patching efforts.
Additionally, organizations should monitor for indicators of compromise and unusual privilege escalation attempts on their networks.
The advisory underscores the importance of maintaining current patch management practices and rapid response capabilities to emerging threats.
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