CVE-2025-55334 is a vulnerability identified in Microsoft Windows 11 Version 25H2 (build 10.0.26200.0) characterized by the cleartext storage of sensitive information within the Windows Kernel. This vulnerability is classified under CWE-312, indicating improper protection of sensitive data at rest. The flaw enables an unauthorized local attacker, who does not require privileges or user interaction, to bypass certain security features by accessing sensitive information stored in cleartext. The vulnerability has a CVSS v3.1 base score of 6.2, reflecting a medium severity level, with a vector indicating local attack vector (AV:L), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and high confidentiality impact (C:H) but no impact on integrity (I:N) or availability (A:N). The scope remains unchanged (S:U). The vulnerability was reserved in August 2025 and published in October 2025, with no known exploits in the wild and no patches currently available. The cleartext storage of sensitive information in the kernel could allow attackers with local access to extract critical data that may facilitate further attacks or privilege escalation. Since the vulnerability does not require elevated privileges or user interaction, it poses a risk in environments where local access is possible, such as shared workstations or compromised endpoints. The absence of patches necessitates interim mitigations to reduce exposure.

For European organizations, the primary impact of CVE-2025-55334 lies in the potential exposure of sensitive kernel-level information, which could be leveraged to bypass security controls or facilitate privilege escalation attacks. This confidentiality breach may compromise sensitive data related to system security mechanisms, user credentials, or cryptographic keys stored in the kernel. Organizations with shared or multi-user environments, such as enterprises, educational institutions, and public sector entities, are particularly at risk if local access controls are weak. The vulnerability does not directly affect system integrity or availability, but the indirect consequences of an attacker gaining elevated access could lead to broader compromise, data theft, or persistence mechanisms. Given the medium severity and lack of known exploits, the immediate threat is moderate; however, the risk escalates if attackers develop exploits or if the vulnerability is combined with other weaknesses. European critical infrastructure operators and organizations handling sensitive data should prioritize awareness and mitigation to prevent local exploitation.

1. Restrict local access to systems running Windows 11 Version 25H2 (build 10.0.26200.0) by enforcing strict physical and logical access controls, including strong authentication and session locking. 2. Monitor and audit local user activities for unusual behavior that may indicate attempts to access kernel memory or sensitive data. 3. Employ endpoint detection and response (EDR) solutions capable of detecting anomalous kernel-level access or privilege escalation attempts. 4. Isolate high-value or sensitive systems to minimize the number of users with local access. 5. Once Microsoft releases patches or updates addressing CVE-2025-55334, prioritize immediate deployment across all affected systems. 6. Educate users and administrators about the risks of local access vulnerabilities and enforce least privilege principles. 7. Consider using virtualization or sandboxing technologies to limit the impact of potential local exploits. 8. Regularly review and update security policies to incorporate emerging threat intelligence related to this vulnerability.