CVE-2025-59278 is a vulnerability classified under CWE-1287, which pertains to improper validation of the specified type of input. This flaw exists in the Windows Authentication Methods component of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The vulnerability allows an attacker who already has authorized local access to the system to escalate their privileges. The root cause is the failure of the authentication subsystem to properly validate the type of input it receives, which can be manipulated to bypass security controls and gain elevated privileges. The CVSS v3.1 score of 7.8 reflects a high-severity issue, with attack vector local (AV:L), low attack complexity (AC:L), requiring privileges (PR:L), no user interaction (UI:N), unchanged scope (S:U), and high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). Although no exploits are currently known in the wild, the vulnerability poses a significant risk because it can lead to full system compromise once exploited. The absence of published patches at this time necessitates proactive mitigation. The vulnerability was reserved in September 2025 and published in October 2025, indicating recent discovery and disclosure.

For European organizations, this vulnerability presents a critical risk especially to those running legacy Windows 10 Version 1809 systems. Successful exploitation allows attackers with local access to gain elevated privileges, potentially leading to full control over affected systems. This can result in unauthorized access to sensitive data, disruption of services, and the ability to deploy further malicious activities such as ransomware or lateral movement within networks. Sectors such as finance, healthcare, government, and critical infrastructure are particularly vulnerable due to the sensitive nature of their data and operations. The impact extends to confidentiality breaches, integrity violations through unauthorized changes, and availability disruptions via system compromise or denial of service. Given the widespread use of Windows 10 in Europe, the vulnerability could affect a broad range of organizations, especially those that have not updated or migrated from older Windows versions.

1. Restrict local access to systems running Windows 10 Version 1809 by enforcing strict physical and network access controls. 2. Implement the principle of least privilege to minimize the number of users with local access and administrative rights. 3. Monitor and audit local authentication attempts and privilege escalation activities to detect potential exploitation attempts early. 4. Prepare for rapid deployment of patches or updates from Microsoft once they become available; subscribe to official Microsoft security advisories. 5. Consider upgrading affected systems to a more recent and supported Windows version where this vulnerability is not present. 6. Employ application whitelisting and endpoint detection and response (EDR) solutions to detect and block suspicious activities related to privilege escalation. 7. Conduct regular security awareness training focusing on the risks of local access and privilege escalation threats.