CVE-2025-55680 is a Time-of-check Time-of-use (TOCTOU) race condition vulnerability identified 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 incorrectly handles timing between the verification of a resource's state and its subsequent use, allowing an attacker to exploit the window between these operations. Specifically, an authorized local attacker with limited privileges can manipulate the timing to gain elevated privileges, bypassing normal security checks. The vulnerability affects confidentiality, integrity, and availability by enabling unauthorized access and control over system resources. The CVSS v3.1 score of 7.8 reflects high severity, with an attack vector requiring local access but low complexity and no user interaction. Although no public exploits are currently known, the flaw's nature makes it a critical concern for organizations relying on Windows 11 25H2, especially those utilizing cloud file synchronization features. The vulnerability is categorized under CWE-367, which pertains to TOCTOU race conditions, a class of bugs that can lead to privilege escalation and other security breaches if not properly mitigated. Microsoft has not yet released patches at the time of this report, emphasizing the need for proactive defensive measures.

The impact of CVE-2025-55680 on European organizations is significant due to the widespread adoption of Windows 11 25H2 in enterprise environments. Successful exploitation allows an attacker with local access and limited privileges to escalate to higher privilege levels, potentially gaining administrative control. This can lead to unauthorized access to sensitive data, modification or deletion of critical files, and disruption of services. In sectors such as finance, healthcare, government, and critical infrastructure, where data confidentiality and system integrity are paramount, this vulnerability could facilitate insider threats or lateral movement by attackers who have initially compromised lower-privileged accounts. The absence of required user interaction increases the risk of automated or stealthy exploitation. Additionally, organizations relying on cloud file synchronization may face increased risk due to the vulnerability residing in the Cloud Files Mini Filter Driver. The potential for widespread impact is heightened by the vulnerability's presence in a core Windows component, making it a valuable target for attackers aiming to compromise European enterprise networks.

To mitigate CVE-2025-55680, European organizations should implement the following specific measures: 1) Monitor Microsoft security advisories closely and apply official patches immediately upon release to address the vulnerability in the Cloud Files Mini Filter Driver. 2) Restrict local user privileges rigorously, ensuring that users have only the minimum necessary permissions to reduce the attack surface for local privilege escalation. 3) Employ application whitelisting and endpoint detection and response (EDR) solutions to detect and block suspicious activities indicative of exploitation attempts. 4) Audit and monitor file system and cloud synchronization activities for anomalies that could signal exploitation of the TOCTOU race condition. 5) Harden system configurations by disabling or limiting the use of cloud file synchronization features where feasible, especially on sensitive or critical systems. 6) Conduct regular security awareness training for administrators and users about the risks of local privilege escalation and the importance of maintaining strict access controls. 7) Implement network segmentation to limit lateral movement opportunities if an attacker gains elevated privileges. These steps, combined with timely patching, will significantly reduce the risk posed by this vulnerability.