CVE-2025-59275 is a vulnerability identified in Microsoft Windows 10 Version 1809 (build 10.0.17763.0) that stems from improper validation of the specified type of input within Windows Authentication Methods. This flaw allows an attacker who already has authorized local access to the system to escalate their privileges. The vulnerability is categorized under CWE-1287, which involves improper validation of input types, potentially leading to memory corruption or logic errors. The CVSS v3.1 base score of 7.8 reflects a high severity, with attack vector being local (AV:L), low attack complexity (AC:L), requiring low privileges (PR:L), and no user interaction (UI:N). The scope is unchanged (S:U), but the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H). This means an attacker can gain elevated privileges, potentially allowing full control over the affected system, including executing arbitrary code, accessing sensitive data, or disrupting system operations. The vulnerability does not require user interaction and can be exploited by any authorized local user, increasing the risk in environments where multiple users share systems or where attackers have gained limited access. No known exploits have been reported in the wild, and no patches have been released at the time of publication, emphasizing the need for proactive mitigation. The vulnerability affects only Windows 10 Version 1809, which remains in use in many enterprise environments despite being an older release. The improper input validation likely involves authentication routines that fail to correctly verify the type or format of data, leading to privilege escalation through manipulation of authentication tokens or credentials.

For European organizations, the impact of CVE-2025-59275 can be significant, particularly in sectors relying on Windows 10 Version 1809 systems for critical operations. Successful exploitation allows an attacker with local access to elevate privileges, potentially leading to full system compromise. This can result in unauthorized access to sensitive data, disruption of services, and the ability to deploy further malware or ransomware. Organizations with shared workstations, remote access solutions, or multi-user environments are particularly vulnerable. The confidentiality of personal and corporate data can be severely impacted, violating GDPR requirements. Integrity of systems and data can be compromised, undermining trust and operational reliability. Availability may also be affected if attackers disrupt authentication services or system stability. The lack of a patch increases the window of exposure, and the high severity score indicates that the threat should be prioritized. European critical infrastructure, government agencies, and enterprises with legacy systems are at heightened risk due to the potential for targeted attacks leveraging this vulnerability.

To mitigate CVE-2025-59275 effectively, European organizations should implement several specific measures beyond generic advice: 1) Restrict local access strictly to trusted users and enforce strong physical and logical access controls, minimizing the number of users with local login capabilities on Windows 10 Version 1809 systems. 2) Employ application whitelisting and endpoint detection and response (EDR) solutions to monitor and block suspicious privilege escalation attempts. 3) Isolate legacy Windows 10 Version 1809 systems from critical network segments and sensitive data repositories to limit lateral movement if compromise occurs. 4) Enforce the principle of least privilege rigorously, ensuring users operate with minimal necessary rights to reduce exploitation potential. 5) Monitor authentication logs and system events for anomalies indicative of privilege escalation attempts, using SIEM tools configured with rules targeting unusual local privilege changes. 6) Plan and expedite migration to supported Windows versions with active security updates, as Windows 10 Version 1809 is an older release with diminishing support. 7) Prepare incident response playbooks specific to local privilege escalation scenarios to enable rapid containment and remediation. 8) Stay alert for official patches or security advisories from Microsoft and apply updates promptly once available. These targeted actions will reduce the attack surface and improve detection and response capabilities against this vulnerability.