CVE-2025-54094 is a vulnerability classified under CWE-843 (Access of Resource Using Incompatible Type, commonly known as type confusion) affecting the Windows Defender Firewall Service in Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The flaw allows an authorized attacker with local access and high privileges to exploit type confusion in the firewall service, enabling them to elevate their privileges further on the system. Type confusion occurs when a program accesses a resource or memory location using an incorrect or incompatible data type, potentially leading to unexpected behavior such as memory corruption or unauthorized access. In this case, the vulnerability could allow an attacker to manipulate the firewall service to gain higher privileges, compromising system security. The CVSS 3.1 base score is 6.7 (medium severity), with attack vector local (AV:L), low attack complexity (AC:L), privileges required high (PR:H), no user interaction (UI:N), and impact on confidentiality, integrity, and availability all rated high (C:H/I:H/A:H). No known exploits are currently reported in the wild, and no patches have been linked yet, indicating the need for vigilance and timely remediation once updates are released. The vulnerability is particularly relevant for organizations still running Windows 10 Version 1809, which, despite being an older release, remains in use in certain environments due to legacy application dependencies or delayed upgrade cycles.

For European organizations, the impact of CVE-2025-54094 can be significant, especially in sectors where Windows 10 Version 1809 is still operational, such as government agencies, healthcare, manufacturing, and critical infrastructure. Successful exploitation allows an attacker with local access and existing high privileges to escalate their privileges further, potentially gaining SYSTEM-level control. This can lead to unauthorized access to sensitive data, disruption of services, and the ability to deploy further malware or ransomware. The compromise of the Windows Defender Firewall Service could also undermine network security controls, increasing the risk of lateral movement within networks. Although exploitation requires local access and high privileges, insider threats or attackers who have already breached perimeter defenses could leverage this vulnerability to deepen their foothold. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the potential for future attacks, especially as threat actors develop proof-of-concept exploits. European organizations with legacy systems or delayed patching practices are particularly vulnerable, and the impact could be exacerbated in environments with weak internal access controls or insufficient monitoring.

1. Prioritize upgrading from Windows 10 Version 1809 to a supported and fully patched version of Windows 10 or Windows 11 to eliminate exposure to this vulnerability. 2. Apply security patches promptly once Microsoft releases an official update addressing CVE-2025-54094. 3. Restrict local administrative access to trusted personnel only and enforce the principle of least privilege to reduce the risk of exploitation by insiders or compromised accounts. 4. Implement robust endpoint detection and response (EDR) solutions to monitor for anomalous behavior related to the Windows Defender Firewall Service and privilege escalation attempts. 5. Conduct regular audits of user privileges and local access rights to identify and remediate excessive permissions. 6. Employ application whitelisting and control execution policies to limit the ability of unauthorized code to run on endpoints. 7. Educate IT staff and security teams about this vulnerability and ensure incident response plans include scenarios involving local privilege escalation. 8. Use network segmentation to limit the impact of a compromised host and prevent lateral movement. 9. Monitor Windows event logs and firewall service logs for unusual activity that could indicate exploitation attempts. 10. Consider deploying host-based firewalls and additional endpoint hardening measures to reduce attack surface.