CVE-2025-54094 is a vulnerability identified in Microsoft Windows 10 Version 1809, specifically in the Windows Defender Firewall Service. The root cause is a type confusion error (CWE-843), where the system accesses a resource using an incompatible data type. This flaw can be exploited by an attacker who already has authorized local access to the system to escalate their privileges to a higher level, potentially SYSTEM or administrative privileges. The vulnerability does not require user interaction and has a low attack complexity, but it does require the attacker to have prior local access with some level of privileges. The CVSS v3.1 base score is 6.7, indicating a medium severity level, with impacts on confidentiality, integrity, and availability (all rated high). The scope is unchanged, meaning the vulnerability affects only the vulnerable component without extending to other components. No public exploits or patches are currently known or available, which suggests that organizations should be proactive in mitigating risk. The affected version is Windows 10 Version 1809 (build 17763.0), an older release that may still be present in legacy systems or environments with delayed upgrade cycles. The vulnerability could allow attackers to bypass security restrictions enforced by the firewall service, potentially leading to unauthorized access to sensitive data or system control. Given the nature of the flaw, exploitation could facilitate further attacks or persistence on compromised systems.

For European organizations, this vulnerability poses a significant risk primarily to environments still running Windows 10 Version 1809, which may include industrial control systems, legacy enterprise applications, or government infrastructure with delayed upgrade policies. Successful exploitation can lead to privilege escalation, allowing attackers to gain administrative control, bypass security controls, and access or modify sensitive data. This could result in data breaches, disruption of critical services, or further lateral movement within networks. The impact is heightened for organizations subject to strict data protection regulations such as GDPR, where unauthorized access to personal data can lead to severe legal and financial penalties. Additionally, sectors such as finance, healthcare, energy, and public administration are particularly sensitive to such escalations due to the critical nature of their operations and data. Although no exploits are currently known in the wild, the existence of this vulnerability increases the attack surface for insider threats or malware that gains initial local access. The medium severity rating reflects the need for local access and the absence of user interaction, limiting remote exploitation but still posing a serious threat in compromised environments.

1. Immediate mitigation should focus on restricting local access to systems running Windows 10 Version 1809, ensuring only trusted users have login privileges. 2. Implement strict access control policies and monitor for unusual privilege escalation attempts or anomalous behavior related to the Defender Firewall Service. 3. Employ application whitelisting and endpoint detection and response (EDR) solutions to detect and block suspicious activities that could exploit this vulnerability. 4. Plan and prioritize upgrading affected systems to a supported and patched version of Windows 10 or later, as this version is out of mainstream support and unlikely to receive official patches. 5. Use network segmentation to limit the spread of potential compromises originating from vulnerable hosts. 6. Regularly audit and review local user accounts and privileges to minimize the risk of insider threats exploiting this flaw. 7. Stay informed on vendor advisories for any forthcoming patches or workarounds and apply them promptly once available. 8. Conduct targeted penetration testing and vulnerability assessments focusing on privilege escalation vectors to identify and remediate weaknesses proactively.