CVE-2025-53808 is a vulnerability classified under CWE-843 (Access of Resource Using Incompatible Type, also known as type confusion) affecting the Windows Defender Firewall Service on Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The vulnerability allows an authorized local attacker to perform privilege escalation by exploiting a flaw where the firewall service accesses resources using an incompatible type, potentially leading to memory corruption or execution of arbitrary code with elevated privileges. The attacker must have local access and some level of privileges (PR:H) but does not require user interaction (UI:N). The vulnerability impacts confidentiality, integrity, and availability (all rated high in the CVSS vector). The CVSS score is 6.7, indicating a medium severity level. No public exploits or patches are currently available, but the vulnerability is published and recognized by Microsoft. The flaw could be leveraged by attackers to bypass security controls and gain SYSTEM-level privileges, which could facilitate further attacks such as installing persistent malware, disabling security features, or accessing sensitive data. Since it affects Windows 10 Version 1809, which is an older but still in-use version, organizations running legacy systems are particularly vulnerable. The vulnerability is significant because the Windows Defender Firewall Service is a core security component, and its compromise undermines the host's security posture.

For European organizations, this vulnerability poses a risk of local privilege escalation on systems running Windows 10 Version 1809, which may still be present in many enterprises, especially in sectors with slower upgrade cycles such as manufacturing, healthcare, and government. Successful exploitation could allow attackers to gain SYSTEM-level privileges, enabling them to disable security controls, access sensitive information, or deploy malware with high persistence. This could lead to data breaches, operational disruption, and compliance violations under regulations like GDPR. The impact is heightened in critical infrastructure environments where Windows 10 1809 may be used in legacy systems controlling industrial processes. The lack of known exploits reduces immediate risk but also means organizations should proactively address the vulnerability before attackers develop reliable exploit code. The medium severity rating suggests a significant but not critical threat, emphasizing the need for timely mitigation to avoid privilege escalation chains in targeted attacks.

1. Prioritize upgrading affected systems from Windows 10 Version 1809 to a supported and patched version of Windows 10 or Windows 11, as Microsoft may not provide patches for this legacy version. 2. If upgrading is not immediately feasible, implement strict local access controls to limit the number of users with local privileges, reducing the attack surface. 3. Employ application whitelisting and endpoint detection and response (EDR) solutions to monitor and block suspicious activities related to privilege escalation attempts. 4. Regularly audit and review user privileges and remove unnecessary administrative rights to minimize potential exploitation. 5. Monitor Windows Defender Firewall Service logs and system event logs for anomalies that could indicate exploitation attempts. 6. Implement network segmentation to isolate legacy systems and limit lateral movement in case of compromise. 7. Stay informed on Microsoft security advisories for any forthcoming patches or mitigations related to this vulnerability. 8. Conduct internal penetration testing focusing on privilege escalation vectors to identify and remediate weaknesses proactively.