CVE-2025-55328 is a race condition vulnerability classified under CWE-362 affecting Microsoft Windows 11 Version 25H2, specifically within the Hyper-V virtualization component. The vulnerability 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—someone with limited privileges on the system—to exploit the timing issue to escalate their privileges to higher levels, potentially SYSTEM or administrator level. The attack vector requires local access with some privileges (PR:L), no user interaction (UI:N), and the scope remains unchanged (S:U). The CVSS v3.1 base score is 7.8, indicating high severity, with impacts rated high on confidentiality, integrity, and availability. Although no exploits are currently known in the wild, the vulnerability poses a significant risk due to the critical role of Hyper-V in managing virtual machines and isolating workloads. Exploitation could allow attackers to bypass security boundaries, gain control over virtualized environments, and compromise sensitive data or system stability. The vulnerability was reserved in August 2025 and published in October 2025, with no patches yet publicly linked, indicating a need for vigilance and rapid response once fixes are released.

For European organizations, this vulnerability presents a substantial risk, particularly for enterprises and government entities relying on Windows 11 25H2 with Hyper-V for virtualization and cloud infrastructure. Successful exploitation could lead to unauthorized privilege escalation, enabling attackers to execute arbitrary code with elevated rights, access sensitive data, disrupt services, or move laterally within networks. This is especially critical for sectors such as finance, healthcare, energy, and public administration, where virtualization is heavily used to optimize resources and isolate workloads. The compromise of Hyper-V could undermine trust in virtualized environments, potentially causing operational disruptions and data breaches. Given the high adoption rate of Windows 11 in Europe and the strategic importance of virtualized infrastructure, the impact could be widespread, affecting confidentiality, integrity, and availability of critical systems.

1. Monitor Microsoft’s security advisories closely and apply official patches immediately upon release to remediate the race condition. 2. Until patches are available, restrict local access to systems running Windows 11 25H2 with Hyper-V enabled, limiting user privileges to the minimum necessary. 3. Implement strict access controls and auditing on Hyper-V hosts to detect unusual privilege escalation attempts or suspicious activity. 4. Use endpoint detection and response (EDR) tools to monitor for exploitation attempts targeting race conditions or privilege escalation. 5. Consider disabling Hyper-V on systems where virtualization is not required to reduce the attack surface. 6. Conduct regular security training for administrators and users about the risks of local privilege escalation vulnerabilities. 7. Employ network segmentation to isolate critical virtualized environments, limiting lateral movement if exploitation occurs. 8. Review and harden system configurations related to Hyper-V and privilege management to minimize exposure.