CVE-2025-59187 is a vulnerability identified in Microsoft Windows 11 Version 25H2 (build 10.0.26200.0) involving improper input validation within the Windows Kernel. The weakness is categorized under CWE-20 (Improper Input Validation), which means the kernel component fails to properly verify or sanitize input data before processing it. This flaw can be exploited by an attacker who already has authorized local access to the system, enabling them to escalate their privileges to a higher level, potentially SYSTEM or kernel-level privileges. The attack vector is local (AV:L), requiring low attack complexity (AC:L) and only limited privileges (PR:L), but no user interaction (UI:N). The scope remains unchanged (S:U), but the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H), indicating that successful exploitation could lead to full system compromise. No public exploits are known at this time, but the vulnerability is critical enough to warrant immediate attention. The absence of patch links suggests that a fix is either pending or in development. The vulnerability's presence in the Windows Kernel makes it particularly dangerous because kernel-level compromise can bypass many security controls and protections. This vulnerability is relevant to organizations running Windows 11 Version 25H2, especially those with multiple users or shared systems where local privilege escalation could facilitate lateral movement or persistence.

For European organizations, this vulnerability poses a significant threat due to the widespread adoption of Windows 11 in enterprise environments, including government, finance, healthcare, and critical infrastructure sectors. Successful exploitation could allow attackers with limited local access—such as through compromised user accounts or insider threats—to escalate privileges and gain full control over affected systems. This could lead to data breaches, disruption of services, installation of persistent malware, or further lateral movement within networks. The high impact on confidentiality, integrity, and availability means sensitive data could be exposed or altered, and critical systems could be rendered inoperative. Given the local attack vector, organizations with strong perimeter defenses but weaker internal controls or endpoint protections may be particularly vulnerable. The lack of known exploits currently provides a window for proactive mitigation, but the vulnerability's severity demands urgent patching and monitoring to prevent exploitation attempts.

1. Monitor Microsoft security advisories closely and apply official patches or updates for Windows 11 Version 25H2 immediately upon release. 2. Restrict local administrative privileges and enforce the principle of least privilege to limit the number of users who can exploit this vulnerability. 3. Implement robust endpoint detection and response (EDR) solutions capable of detecting unusual privilege escalation behaviors. 4. Harden local access controls, including strong authentication mechanisms and account lockout policies to prevent unauthorized local access. 5. Conduct regular audits of user accounts and permissions to identify and remediate excessive privileges. 6. Employ application whitelisting and kernel integrity monitoring to detect unauthorized kernel-level changes. 7. Educate users and administrators about the risks of local privilege escalation and the importance of reporting suspicious activity. 8. Use virtualization-based security features available in Windows 11 to isolate critical kernel components where possible. 9. Prepare incident response plans specifically addressing privilege escalation scenarios to enable rapid containment and remediation.