CVE-2025-55328 is a vulnerability classified under CWE-362 (Race Condition) affecting Microsoft Windows 11 Version 25H2, specifically within the Hyper-V virtualization component. The issue stems from improper synchronization when multiple threads or processes concurrently access shared resources, leading to a race condition. This flaw allows an authorized local attacker to exploit the timing window to elevate privileges, potentially gaining SYSTEM-level access. The vulnerability does not require user interaction but does require local privileges, meaning an attacker must already have some level of access to the system. The CVSS v3.1 base score is 7.8, reflecting high severity due to the combined impact on confidentiality, integrity, and availability. No public exploits are currently known, but the vulnerability is published and recognized by Microsoft. The absence of a patch link suggests remediation is pending or forthcoming. Hyper-V is widely used in enterprise environments for virtualization, making this vulnerability particularly relevant for organizations relying on Windows 11 25H2 with Hyper-V enabled. Exploitation could allow attackers to bypass security controls, execute arbitrary code with elevated privileges, and compromise virtualized environments or host systems.

For European organizations, the impact of CVE-2025-55328 can be significant, especially in sectors heavily reliant on virtualization technologies such as finance, government, healthcare, and critical infrastructure. Successful exploitation could lead to unauthorized privilege escalation, enabling attackers to deploy malware, access sensitive data, disrupt services, or move laterally within networks. The compromise of Hyper-V hosts could affect multiple virtual machines, amplifying the scope of impact. Given the high adoption rate of Windows 11 and Hyper-V in European enterprises, this vulnerability poses a risk to confidentiality, integrity, and availability of critical systems. Additionally, organizations with strict regulatory requirements (e.g., GDPR) may face compliance challenges if breaches occur due to this flaw. The lack of known exploits currently reduces immediate risk but does not eliminate the threat, especially as attackers often develop exploits rapidly after public disclosure.

Organizations should prepare to deploy official patches from Microsoft as soon as they become available. Until then, practical mitigation steps include restricting local access to systems running Windows 11 25H2 with Hyper-V enabled, enforcing the principle of least privilege to limit who can log in locally, and monitoring system logs for unusual activity related to Hyper-V processes. Disabling Hyper-V on systems where it is not required can reduce the attack surface. Network segmentation and strict access controls around virtualization hosts can help contain potential breaches. Employing endpoint detection and response (EDR) solutions to detect privilege escalation attempts and anomalous behavior is recommended. Regularly updating security policies and conducting user awareness training about the risks of local privilege escalation can further reduce exposure. Finally, organizations should maintain an inventory of affected systems to prioritize remediation efforts effectively.