CVE-2025-53808 is a vulnerability classified under CWE-843 (Access of Resource Using Incompatible Type, or 'Type Confusion') affecting the Windows Defender Firewall Service in Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The vulnerability occurs when the firewall service improperly handles resource types, allowing an attacker with authorized local access and high privileges to exploit type confusion to elevate their privileges further. This can lead to arbitrary code execution within the context of the firewall service, which runs with elevated system privileges, thereby compromising system confidentiality, integrity, and availability. The attack vector is local, requiring the attacker to have existing high-level privileges, but no user interaction is necessary. The vulnerability was published on September 9, 2025, with a CVSS v3.1 base score of 6.7, reflecting medium severity due to the requirement for local privileged access and the absence of known exploits in the wild. No patches are currently linked, indicating that organizations should be vigilant for updates. The flaw could be leveraged to bypass security controls enforced by the firewall service, potentially allowing attackers to disable or manipulate firewall rules, facilitating further attacks or persistence.

For European organizations, the impact of CVE-2025-53808 can be significant, particularly in environments where Windows 10 Version 1809 remains in use, such as legacy systems in government, healthcare, finance, and critical infrastructure sectors. Successful exploitation could allow attackers to escalate privileges locally, compromising sensitive data and system controls. This could lead to unauthorized changes in firewall configurations, enabling lateral movement, data exfiltration, or disruption of network defenses. The elevated privileges could also facilitate deployment of malware or ransomware, increasing operational risk. Although exploitation requires local access with high privileges, insider threats or attackers who have already gained partial access could leverage this vulnerability to deepen their foothold. The absence of known exploits in the wild reduces immediate risk but does not eliminate the threat, especially as attackers often develop exploits after public disclosure. Organizations with strict regulatory requirements for data protection and system integrity in Europe must prioritize addressing this vulnerability to avoid compliance violations and reputational damage.

1. Monitor Microsoft security advisories closely and apply official patches or updates as soon as they become available for Windows 10 Version 1809 systems. 2. Restrict local administrative access to trusted personnel only, employing the principle of least privilege to minimize the number of users with high privileges. 3. Implement robust endpoint detection and response (EDR) solutions to monitor for unusual privilege escalation attempts or modifications to firewall service processes. 4. Conduct regular audits of firewall configurations and system logs to detect unauthorized changes or suspicious activities. 5. Consider upgrading affected systems to a supported and more recent Windows version where this vulnerability is not present or has been remediated. 6. Employ application whitelisting and code integrity policies to prevent unauthorized code execution even if privilege escalation occurs. 7. Harden local access controls by using multifactor authentication for administrative accounts and limiting physical access to critical systems. 8. Educate IT staff and users about the risks of privilege escalation vulnerabilities and the importance of maintaining updated systems.