CVE-2025-62567 is a medium-severity integer underflow vulnerability classified under CWE-191, affecting Microsoft Windows 10 Version 1809, specifically in the Hyper-V virtualization component. The vulnerability stems from improper handling of integer values within Hyper-V, leading to an underflow condition where integer values wrap around unexpectedly. This flaw can be triggered by an authorized attacker with low privileges over a network, causing a denial of service (DoS) by disrupting Hyper-V operations, potentially crashing or destabilizing virtual machines or the host hypervisor service. The CVSS v3.1 score of 5.3 reflects a network attack vector (AV:N), high attack complexity (AC:H), low privileges required (PR:L), no user interaction (UI:N), unchanged scope (S:U), no impact on confidentiality or integrity (C:N, I:N), but high impact on availability (A:H). The vulnerability does not require user interaction and is exploitable remotely but demands specific conditions and privileges, which limits widespread exploitation. No known exploits have been reported in the wild, and no patches are currently available, indicating the need for proactive mitigation. The vulnerability affects Windows 10 Version 1809 build 10.0.17763.0, a version still in use in some enterprise environments despite being out of mainstream support. The lack of patch links suggests that Microsoft has not yet released an official fix, emphasizing the importance of alternative risk reduction strategies. The integer underflow can cause wraparound errors in memory or resource management within Hyper-V, leading to service crashes or denial of service conditions that impact availability but do not compromise data confidentiality or integrity.

For European organizations, the primary impact of CVE-2025-62567 is the potential for denial of service attacks against Hyper-V virtualization hosts running Windows 10 Version 1809. This can disrupt critical virtualized workloads, including servers, applications, and infrastructure services, leading to operational downtime and potential business continuity issues. Organizations relying on Hyper-V for cloud services, internal virtualization, or hosting critical applications may experience service interruptions. Although the vulnerability does not allow data theft or modification, availability loss can affect productivity, customer service, and compliance with service level agreements. Given that Windows 10 Version 1809 is an older release, some organizations may still use it in legacy environments, increasing their exposure. The requirement for low privileges and network access means that insider threats or compromised internal systems could exploit this vulnerability. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits once the vulnerability becomes widely known. European sectors such as finance, healthcare, manufacturing, and government, which often use virtualization extensively, could be particularly impacted if mitigation is not applied.

1. Upgrade affected systems to a supported and patched version of Windows, preferably the latest Windows 10 or Windows 11 releases, as Windows 10 Version 1809 is out of mainstream support and unlikely to receive patches. 2. Restrict network access to Hyper-V management interfaces and related services using network segmentation, firewalls, and access control lists to limit exposure to authorized personnel only. 3. Implement strict privilege management to ensure that only trusted users have low-level privileges that could be leveraged to exploit this vulnerability. 4. Monitor Hyper-V host systems for unusual crashes, service restarts, or performance degradation that could indicate exploitation attempts. 5. Employ intrusion detection and prevention systems (IDS/IPS) tuned to detect anomalous Hyper-V network traffic or known attack patterns once available. 6. Consider isolating legacy Windows 10 Version 1809 Hyper-V hosts from critical production environments until they can be upgraded or patched. 7. Maintain up-to-date backups of virtual machines and host configurations to enable rapid recovery in case of denial of service incidents. 8. Stay informed on Microsoft advisories for any forthcoming patches or mitigations related to this CVE.