CVE-2025-55336 is a vulnerability identified in the Windows Cloud Files Mini Filter Driver component of Microsoft Windows 11 Version 25H2 (build 10.0.26200.0). The flaw is classified under CWE-200, indicating exposure of sensitive information to unauthorized actors. Specifically, an authorized attacker with low privileges on the local system can exploit this vulnerability to disclose sensitive information without requiring user interaction. The attack vector is local, meaning the attacker must have some level of access to the affected machine, but the required privileges are low, increasing the risk within environments where multiple users share systems or where local access controls are weak. The vulnerability does not affect system integrity or availability, focusing solely on confidentiality. The CVSS v3.1 base score is 5.5 (medium severity), with metrics indicating low attack complexity, low privileges required, no user interaction, and a confidentiality impact rated as high. No public exploits or patches are currently available, and the vulnerability was published on October 14, 2025. The Cloud Files Mini Filter Driver is involved in managing cloud file synchronization and caching, so the exposure could involve sensitive cached data or metadata. This vulnerability highlights the importance of securing local access and monitoring for unauthorized data disclosures in Windows 11 environments.

For European organizations, the primary impact of CVE-2025-55336 is the potential unauthorized disclosure of sensitive information stored or cached locally on Windows 11 Version 25H2 systems. This could include corporate documents, credentials, or other confidential data managed by cloud file synchronization services. The vulnerability requires local access with low privileges, so insider threats or compromised user accounts pose the greatest risk. Organizations with shared workstations, remote desktop environments, or insufficient endpoint security controls are particularly vulnerable. While the vulnerability does not allow for system takeover or denial of service, the confidentiality breach could lead to data leaks, regulatory non-compliance (e.g., GDPR), and reputational damage. Critical sectors such as finance, healthcare, and government agencies in Europe that rely heavily on Windows 11 desktops and cloud file integration may face increased risk. The absence of known exploits in the wild provides a window for proactive mitigation, but the lack of an available patch necessitates heightened vigilance.

1. Restrict local access to Windows 11 Version 25H2 systems by enforcing strict user account controls and minimizing the number of users with local login privileges. 2. Implement robust endpoint detection and response (EDR) solutions to monitor for unusual file access patterns or attempts to exploit local vulnerabilities. 3. Use application whitelisting and privilege management to limit the ability of low-privilege users to access sensitive cloud file cache locations. 4. Educate users about the risks of local credential theft and enforce strong authentication mechanisms, including multi-factor authentication for local accounts where possible. 5. Until a patch is released, consider isolating critical systems or disabling unnecessary cloud file synchronization features if feasible. 6. Maintain up-to-date backups and audit logs to detect and respond to potential data disclosures. 7. Monitor Microsoft security advisories closely and apply patches promptly once available. 8. Conduct regular security assessments focusing on local privilege escalation and information disclosure vectors within Windows environments.