CVE-2025-55679 is a vulnerability identified in the Windows Kernel of Microsoft Windows 11 Version 25H2 (build 10.0.26200.0). The root cause is improper input validation (CWE-20), which allows an unauthorized attacker with local access to cause information disclosure. Specifically, the kernel component fails to properly validate inputs, leading to leakage of sensitive data from kernel memory or other protected areas. The vulnerability does not require any privileges or user interaction, but the attacker must have local access to the system. The CVSS v3.1 score is 5.1 (medium), reflecting the high attack complexity and local attack vector, but with high confidentiality impact. There are no known exploits in the wild at the time of publication, and no patches have been linked yet. This vulnerability could be leveraged by attackers who have gained local access through other means (e.g., physical access, compromised accounts) to escalate information gathering capabilities. The flaw does not affect system integrity or availability, limiting the scope to confidentiality breaches. The vulnerability is categorized under CWE-20 (Improper Input Validation), indicating that the kernel does not adequately check input parameters before processing, which leads to unexpected behavior and data leakage.

For European organizations, the primary impact of CVE-2025-55679 is unauthorized disclosure of sensitive information on Windows 11 Version 25H2 systems. This could include leakage of kernel memory contents or other protected data, potentially exposing credentials, cryptographic keys, or other confidential information. Such data leakage can facilitate further attacks, including privilege escalation or lateral movement within networks. Sectors handling sensitive personal data (e.g., healthcare, finance, government) are particularly at risk due to GDPR and other privacy regulations. The requirement for local access limits remote exploitation but does not eliminate risk, especially in environments with shared workstations, remote desktop access, or insider threats. The medium severity indicates a moderate risk level, but the confidentiality impact could be significant depending on what information is disclosed. Organizations relying heavily on Windows 11 25H2 should assess exposure and prepare for patch deployment. The lack of known exploits reduces immediate risk but does not preclude future weaponization.

1. Monitor Microsoft’s official channels for patches addressing CVE-2025-55679 and apply them promptly once available. 2. Restrict local access to Windows 11 25H2 systems by enforcing strict physical security controls and limiting user accounts with local login privileges. 3. Implement robust endpoint detection and response (EDR) solutions to detect unusual local activity indicative of exploitation attempts. 4. Use application whitelisting and privilege management to reduce the risk of attackers gaining local access or executing unauthorized code. 5. Conduct regular audits of user accounts and local access logs to identify suspicious behavior. 6. Educate users about the risks of local access and insider threats, emphasizing the importance of safeguarding credentials and devices. 7. Consider network segmentation to isolate critical systems running Windows 11 25H2 from less secure environments. 8. Employ encryption and data protection mechanisms to minimize the impact of any potential data disclosure. 9. Prepare incident response plans that include scenarios involving local information disclosure vulnerabilities. 10. Evaluate alternative OS versions or configurations if patching is delayed or unavailable.