CVE-2026-20825 is a vulnerability identified in Microsoft Windows 10 Version 1809, specifically affecting the Hyper-V virtualization platform. The root cause is improper access control (CWE-284), which allows an attacker who already has authorized local access with high privileges to disclose sensitive information from the system. This vulnerability does not require user interaction and does not impact system integrity or availability, focusing solely on confidentiality breaches. The CVSS v3.1 base score is 4.4, reflecting a medium severity level due to the requirement for local access and elevated privileges. The vulnerability could be exploited by an attacker who has administrative rights on the affected system to extract information that should otherwise be protected by access controls within Hyper-V. Although no known exploits are currently reported in the wild, the vulnerability poses a risk in environments where multiple users share access or where administrative accounts could be compromised. The lack of a patch link suggests that remediation may still be pending or that organizations should monitor for updates from Microsoft. This vulnerability highlights the importance of strict access control policies and monitoring in virtualized environments, especially those using legacy Windows 10 versions.

For European organizations, the primary impact of CVE-2026-20825 is the potential unauthorized disclosure of sensitive information within virtualized environments running Windows 10 Version 1809 Hyper-V. This could lead to leakage of confidential data, intellectual property, or security-sensitive information, which may facilitate further attacks or compliance violations under regulations such as GDPR. Organizations relying on virtualization for critical workloads or multi-tenant environments are particularly at risk. The requirement for local high privilege access reduces the likelihood of remote exploitation but increases the risk from insider threats or compromised administrative accounts. The vulnerability does not affect system integrity or availability, so operational disruption is unlikely. However, the confidentiality breach could undermine trust and lead to reputational damage or regulatory penalties if sensitive data is exposed. European sectors with high virtualization usage, such as finance, healthcare, and government, may face elevated risks due to the sensitivity of their data and regulatory scrutiny.

To mitigate CVE-2026-20825, European organizations should implement strict access control policies limiting local administrative privileges to only trusted personnel. Employ the principle of least privilege to reduce the number of users with high-level access to Hyper-V hosts. Monitor and audit administrative activities on Hyper-V systems to detect unauthorized access attempts or suspicious behavior. Segregate virtualized environments and sensitive workloads to minimize the impact of potential information disclosure. Ensure that endpoint security solutions are in place to detect and prevent privilege escalation or lateral movement by attackers. Organizations should track Microsoft's security advisories closely and apply patches or updates promptly once available. Additionally, consider upgrading from Windows 10 Version 1809 to a more recent, supported version of Windows 10 or Windows 11 that may have addressed this vulnerability. Regularly review and update virtualization security configurations and conduct penetration testing to identify potential weaknesses in access controls.