CVE-2025-54091 is a high-severity vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0), specifically affecting the Hyper-V virtualization component. The root cause is an integer overflow or wraparound condition (CWE-190) within Hyper-V. This type of flaw occurs when an arithmetic operation attempts to create a numeric value that exceeds the maximum size the variable can hold, causing it to wrap around to an unexpected value. In this context, the vulnerability allows an authorized attacker with local access and limited privileges (PR:L) to exploit the overflow to escalate their privileges on the host system. The CVSS v3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability (all rated high), with low attack complexity and no user interaction required. The vulnerability does not require user interaction (UI:N) but does require local access and some privileges, indicating it is not remotely exploitable without prior access. No known exploits are currently reported in the wild, and no patches have been linked yet, suggesting that mitigation may rely on vendor updates once available. The vulnerability could allow attackers to bypass security boundaries enforced by Hyper-V, potentially gaining SYSTEM-level privileges, which could lead to full control over the host machine and any virtual machines running on it. This is particularly critical in environments relying on Hyper-V for virtualization and isolation.

For European organizations, the impact of CVE-2025-54091 could be significant, especially for enterprises and service providers using Windows 10 Version 1809 with Hyper-V for virtualization. Privilege escalation vulnerabilities in Hyper-V undermine the isolation between virtual machines and the host, potentially allowing attackers to compromise multiple workloads or sensitive data hosted on virtualized infrastructure. This could lead to data breaches, disruption of critical services, and lateral movement within networks. Organizations in sectors such as finance, healthcare, government, and critical infrastructure are particularly at risk due to the sensitive nature of their data and the reliance on virtualization for operational efficiency and security. Moreover, since Windows 10 Version 1809 is an older release, some organizations may still be running it due to legacy application dependencies, increasing their exposure. The lack of known exploits in the wild currently provides a window for proactive mitigation, but the high severity score indicates that once exploits emerge, the threat landscape could rapidly escalate.

1. Immediate assessment of all systems running Windows 10 Version 1809 with Hyper-V enabled should be conducted to identify vulnerable hosts. 2. Where possible, upgrade affected systems to a more recent, supported Windows version that includes security fixes for this vulnerability. 3. Apply any vendor patches or security updates as soon as they become available from Microsoft. 4. Restrict local access to systems running Hyper-V to trusted administrators only, minimizing the risk of an attacker gaining the required privileges to exploit this vulnerability. 5. Implement strict access controls and monitoring on Hyper-V hosts to detect unusual privilege escalation attempts or suspicious activity. 6. Use application whitelisting and endpoint detection and response (EDR) solutions to identify and block exploitation attempts. 7. Review and harden Hyper-V configuration settings to reduce attack surface, including disabling unnecessary features or services. 8. Conduct regular security audits and penetration testing focused on virtualization infrastructure to identify and remediate weaknesses proactively.