CVE-2025-55680 identifies a time-of-check to time-of-use (TOCTOU) race condition vulnerability in the Windows Cloud Files Mini Filter Driver component of Microsoft Windows 11 Version 25H2 (build 10.0.26200.0). This vulnerability arises when the system performs a security check on a resource or file and then uses that resource without revalidating it, allowing an attacker to manipulate the resource state between the check and use phases. Specifically, the race condition exists in the Cloud Files Mini Filter Driver, which manages cloud file synchronization and caching. An authorized local attacker with limited privileges can exploit this flaw by triggering the race condition to elevate their privileges to a higher level, potentially SYSTEM or administrator. The vulnerability does not require user interaction and has a low attack complexity, but it does require local access and some privileges. The CVSS v3.1 score of 7.8 reflects high impact on confidentiality, integrity, and availability, meaning successful exploitation could lead to full system compromise, unauthorized data access, or disruption of services. No public exploits or patches were available at the time of publication, but the vulnerability is officially recognized and tracked by Microsoft and CVE databases. The flaw is categorized under CWE-367, which covers TOCTOU race conditions, a common class of bugs that can be difficult to detect and mitigate due to timing dependencies. This vulnerability is particularly concerning because the Cloud Files Mini Filter Driver is integral to Windows' handling of cloud storage files, which are widely used in enterprise environments. Attackers exploiting this could bypass security controls and gain persistent elevated access on affected systems.

For European organizations, the impact of CVE-2025-55680 is significant. Many enterprises and public sector entities rely on Windows 11 25H2 for desktop and server environments, especially in industries such as finance, healthcare, manufacturing, and government. Exploitation could allow attackers to escalate privileges from a low-level user account to administrative or SYSTEM level, enabling them to install malware, exfiltrate sensitive data, disrupt operations, or move laterally within networks. The vulnerability affects confidentiality by potentially exposing sensitive information, integrity by allowing unauthorized modification of system files or configurations, and availability by enabling denial-of-service conditions through system compromise. Given the local attack vector, insider threats or attackers who gain initial foothold via phishing or other means could leverage this vulnerability to deepen their access. The lack of user interaction requirement increases the risk of automated or stealthy exploitation. The absence of known exploits in the wild currently reduces immediate risk, but the high severity and ease of exploitation once local access is obtained make this a critical concern for European organizations to address proactively.

1. Apply official Microsoft patches immediately once they are released for Windows 11 Version 25H2 to remediate the TOCTOU race condition in the Cloud Files Mini Filter Driver. 2. Until patches are available, restrict local user privileges to the minimum necessary, especially limiting access to accounts that can interact with cloud file synchronization features. 3. Implement strict application whitelisting and endpoint protection to detect and block suspicious local privilege escalation attempts. 4. Monitor system logs and security event logs for unusual activity related to the Cloud Files Mini Filter Driver or privilege escalation attempts. 5. Employ network segmentation to limit lateral movement opportunities if a local compromise occurs. 6. Educate users and administrators about the risk of local privilege escalation vulnerabilities and enforce strong access controls. 7. Consider disabling or restricting cloud file synchronization features if not essential, to reduce the attack surface. 8. Use advanced endpoint detection and response (EDR) tools capable of detecting race condition exploitation patterns. 9. Regularly audit and review user privileges and system configurations to ensure compliance with least privilege principles.