CVE-2025-59275 is a vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0) that involves improper validation of the specified type of input within Windows Authentication Methods. This flaw allows an authorized local attacker—meaning someone with existing access to the system but with limited privileges—to escalate their privileges to a higher level, potentially SYSTEM or administrative rights. The root cause is a failure in the input validation logic that governs authentication processes, which can be manipulated to bypass intended security checks. The vulnerability is categorized under CWE-1287 (Improper Validation of Specified Type of Input), with related concerns noted under CWE-125 (Out-of-bounds Read) and CWE-122 (Heap-based Buffer Overflow), indicating memory safety issues that could be exploited to corrupt memory or execute arbitrary code. The CVSS v3.1 base score is 7.8, reflecting high severity due to the combination of local attack vector (AV:L), low attack complexity (AC:L), required privileges (PR:L), no user interaction (UI:N), and high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). No public exploits are currently known, but the vulnerability's characteristics suggest it could be weaponized by attackers with local access to gain full control over affected systems. The vulnerability was reserved on 2025-09-11 and published on 2025-10-14, but no patches have been linked yet, indicating that mitigation may require vigilance and interim controls until official fixes are released.

For European organizations, the impact of CVE-2025-59275 is significant. Successful exploitation allows attackers with local access to elevate privileges, potentially gaining administrative control over critical systems. This can lead to unauthorized access to sensitive data, disruption of services, and the ability to deploy further malware or ransomware. Sectors such as government, finance, healthcare, and critical infrastructure are particularly at risk due to their reliance on Windows 10 systems and the sensitive nature of their data and operations. The vulnerability undermines the confidentiality, integrity, and availability of affected systems, increasing the risk of data breaches, operational downtime, and compliance violations under regulations like GDPR. Since exploitation requires local access, insider threats or attackers who have already compromised lower-privileged accounts pose the greatest risk. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially as attackers may develop exploits once patches are released or if the vulnerability is reverse-engineered.

1. Apply official security patches from Microsoft as soon as they become available for Windows 10 Version 1809 systems. 2. Until patches are released, restrict local access to systems by enforcing strict physical and network access controls, including limiting administrative privileges and using multi-factor authentication for local logins. 3. Monitor system logs and security event data for unusual privilege escalation attempts or authentication anomalies. 4. Employ endpoint detection and response (EDR) solutions capable of detecting suspicious local activity indicative of exploitation attempts. 5. Consider upgrading affected systems to a more recent, supported Windows version that does not contain this vulnerability, as Windows 10 Version 1809 is an older release with limited support. 6. Conduct regular security awareness training to reduce insider threat risks and ensure users understand the importance of safeguarding credentials and access. 7. Implement application whitelisting and least privilege principles to limit the impact of any successful local compromise. 8. Use virtualization-based security features and Windows Defender Credential Guard where possible to add layers of protection around authentication processes.