CVE-2025-55699 is an information disclosure vulnerability classified under CWE-200 affecting Microsoft Windows 11 Version 25H2 (build 10.0.26200.0). The vulnerability resides in the Windows Kernel, where an authorized attacker with local privileges can exploit the flaw to disclose sensitive information. The vulnerability does not require user interaction and does not affect system integrity or availability, but it compromises confidentiality by allowing unauthorized access to protected data. The attack vector is local, meaning the attacker must have some level of access to the system, such as a standard user account or higher. The CVSS 3.1 base score is 5.5, with vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N, indicating that the attack is relatively low complexity but requires privileges and local access. No known exploits have been reported in the wild, and no patches have been published at the time of disclosure. The vulnerability could be leveraged in scenarios involving insider threats, compromised user accounts, or lateral movement within a network. Because the flaw is in the kernel, the exposed information could be critical system or user data that could facilitate further attacks or data breaches. Organizations should monitor for unusual local activity and prepare to deploy patches once available.

For European organizations, this vulnerability poses a moderate risk primarily to confidentiality. Sensitive information exposure could lead to data breaches, intellectual property theft, or leakage of credentials that facilitate further compromise. Organizations with high-value data, such as financial institutions, healthcare providers, and government agencies, are at greater risk. Since exploitation requires local access and privileges, the threat is heightened in environments where endpoint security is weak or insider threats are possible. The vulnerability does not affect system integrity or availability, so direct disruption or damage is unlikely. However, the confidentiality breach could have regulatory and reputational consequences under GDPR and other data protection laws. The lack of known exploits reduces immediate risk but also means organizations should proactively prepare defenses. The impact is more significant in environments with many Windows 11 25H2 endpoints, especially where users have local privileges or where attackers could gain such access through phishing or lateral movement.

1. Restrict local access to Windows 11 25H2 systems by enforcing strict access controls and least privilege principles. 2. Monitor and audit local user activities for unusual behavior that could indicate exploitation attempts. 3. Harden endpoint security by deploying advanced endpoint detection and response (EDR) solutions capable of detecting kernel-level anomalies. 4. Implement network segmentation to limit lateral movement opportunities for attackers who gain local access. 5. Educate users about the risks of privilege misuse and insider threats. 6. Prepare for rapid deployment of Microsoft patches once released by maintaining an up-to-date patch management process. 7. Use application whitelisting and restrict installation of unauthorized software to reduce the attack surface. 8. Employ multi-factor authentication to reduce the risk of compromised credentials leading to local access. 9. Regularly back up critical data and verify backup integrity to mitigate potential follow-on attacks. 10. Engage in threat hunting focused on kernel-level information disclosure indicators.