CVE-2025-55699 is an information disclosure vulnerability classified under CWE-200 affecting the Windows 11 Version 25H2 kernel (build 10.0.26200.0). The vulnerability allows an authorized local attacker with low privileges to disclose sensitive information stored or processed within the Windows kernel. The flaw arises from improper handling of sensitive data in kernel memory or kernel-mode components, enabling attackers to read data they should not have access to. The vulnerability does not require user interaction and does not allow modification of data or disruption of system availability, limiting its impact to confidentiality breaches. The CVSS v3.1 score is 5.5 (medium), reflecting the local attack vector (AV:L), low attack complexity (AC:L), and the need for privileges (PR:L), but no user interaction (UI:N). The scope remains unchanged (S:U), and the impact is high on confidentiality (C:H) but none on integrity (I:N) or availability (A:N). There are no known exploits in the wild, and no patches have been published at the time of disclosure. This vulnerability could be leveraged as part of a multi-stage attack to gather sensitive kernel information, potentially aiding privilege escalation or evasion techniques. Organizations running Windows 11 25H2 should monitor for updates and consider limiting local access to trusted users only.

For European organizations, the primary impact of CVE-2025-55699 is the potential unauthorized disclosure of sensitive kernel-level information, which could include cryptographic keys, system configurations, or other confidential data. This exposure could facilitate further attacks such as privilege escalation or lateral movement within networks. Organizations with multi-user environments, shared workstations, or those that allow local access to less-trusted users are particularly vulnerable. While the vulnerability does not directly affect system integrity or availability, the confidentiality breach could undermine trust in system security and compliance with data protection regulations like GDPR. Critical sectors such as finance, healthcare, government, and infrastructure that rely heavily on Windows 11 endpoints may face increased risk if attackers exploit this vulnerability as part of a broader attack chain. The lack of known exploits currently reduces immediate risk, but the medium severity and kernel-level nature warrant proactive mitigation.

1. Restrict local access to Windows 11 25H2 systems to trusted and authorized personnel only, minimizing the attack surface. 2. Employ strict user privilege management, ensuring users operate with the least privilege necessary to reduce the chance of exploitation. 3. Monitor system logs and kernel-level events for unusual access patterns or attempts to read sensitive memory regions. 4. Use endpoint detection and response (EDR) solutions capable of detecting anomalous kernel-level activities. 5. Implement network segmentation to limit lateral movement if local compromise occurs. 6. Stay informed about Microsoft security advisories and apply patches immediately once they become available. 7. Consider deploying application control or virtualization-based security features in Windows 11 to isolate critical processes. 8. Conduct regular security audits and penetration testing focusing on local privilege escalation and information disclosure vectors. These steps go beyond generic advice by focusing on local access control, monitoring, and readiness for patch deployment.