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 vulnerability is classified under CWE-200, indicating an exposure of sensitive information to unauthorized actors. Specifically, the flaw allows an attacker who already has some level of local authorization (low privileges) to access sensitive information that should be protected. The vulnerability does not require user interaction to be exploited and does not affect system integrity or availability, but it compromises confidentiality. The CVSS 3.1 base score is 5.5 (medium severity), with vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N, meaning the attack vector is local, attack complexity is low, privileges required are low, no user interaction is needed, and the impact is high on confidentiality only. The vulnerability stems from improper handling or filtering of sensitive data by the Cloud Files Mini Filter Driver, which is responsible for managing cloud file synchronization and caching on Windows 11. This flaw could allow an attacker to read sensitive cached or synchronized cloud file metadata or contents that should be restricted. No public exploits or patches are currently available, but the vulnerability is published and recognized by Microsoft. Organizations using Windows 11 25H2 with cloud file integration features should be aware of this risk and prepare to apply mitigations and patches once released.

For European organizations, the primary impact of CVE-2025-55336 is the unauthorized disclosure of sensitive information stored or synchronized via cloud file services on Windows 11 25H2 systems. This could include corporate documents, personal data, or other confidential information cached locally by the Cloud Files Mini Filter Driver. Such data exposure can lead to privacy violations, intellectual property theft, or compliance breaches under regulations like GDPR. Since the vulnerability requires local access with low privileges, insider threats or compromised user accounts pose the greatest risk. The lack of impact on integrity or availability means operational disruption is unlikely, but confidentiality breaches can still have serious reputational and legal consequences. Organizations relying heavily on Windows 11 25H2 in environments with multiple users or shared devices are particularly vulnerable. The absence of known exploits in the wild reduces immediate risk but also means attackers could develop exploits in the future. Overall, the vulnerability presents a moderate risk that must be managed proactively to protect sensitive data in European enterprises.

1. Restrict local user privileges to the minimum necessary, especially on systems running Windows 11 25H2 with cloud file synchronization enabled, to reduce the risk of unauthorized local access. 2. Implement strict access controls and monitoring on endpoints to detect unusual local activity that could indicate exploitation attempts. 3. Disable or limit cloud file synchronization features on devices where not required, reducing the attack surface related to the Cloud Files Mini Filter Driver. 4. Prepare for rapid deployment of security patches from Microsoft once available by maintaining an up-to-date patch management process. 5. Conduct regular audits of sensitive data stored or cached locally to identify and protect critical information. 6. Educate users about the risks of local privilege misuse and enforce strong endpoint security policies. 7. Use endpoint detection and response (EDR) tools to monitor for suspicious behaviors related to file system filter drivers. 8. Consider network segmentation and device hardening to limit lateral movement if local compromise occurs. These measures go beyond generic advice by focusing on the specific context of local privilege exploitation and cloud file synchronization components.