CVE-2025-54109 is a vulnerability classified under CWE-843 (Access of Resource Using Incompatible Type, also known as type confusion) affecting the Windows Defender Firewall Service in Microsoft Windows 10 Version 1507 (build 10.0.10240.0). This vulnerability allows an attacker who already has authorized local access with high privileges to exploit the improper handling of resource types within the firewall service. Type confusion occurs when the software incorrectly interprets a resource or object as a different type than intended, which can lead to unexpected behavior such as memory corruption or execution of arbitrary code. In this case, the flaw enables privilege escalation, allowing the attacker to gain higher system privileges than initially granted. The vulnerability does not require user interaction but does require the attacker to have local authenticated access, limiting remote exploitation. The CVSS v3.1 base score is 6.7, indicating a medium severity level with high impact on confidentiality, integrity, and availability. The vulnerability was publicly disclosed on September 9, 2025, with no known exploits in the wild at the time of publication. Since the affected version is an early release of Windows 10 (Version 1507), which is largely superseded by newer versions, the exposure is primarily to legacy systems that have not been updated. The vulnerability's exploitation could allow attackers to bypass security controls enforced by the firewall service, potentially leading to full system compromise or disruption of firewall protections. No official patches or mitigation links were provided at the time of disclosure, emphasizing the need for system upgrades or workarounds. This vulnerability highlights the risks associated with legacy operating systems and the importance of maintaining updated software to avoid exploitation of known flaws.

The impact of CVE-2025-54109 is significant for organizations still operating Windows 10 Version 1507, as it allows an attacker with existing local high privileges to escalate those privileges further, potentially gaining full system control. This can lead to unauthorized access to sensitive data (confidentiality impact), modification or deletion of critical system files or configurations (integrity impact), and disruption or disabling of security services like the firewall (availability impact). The elevated privileges could enable attackers to install persistent malware, disable security controls, or move laterally within the network. Although the vulnerability requires local access and prior authentication, environments with multiple users or shared systems are at higher risk. Legacy systems in industrial, governmental, or specialized environments that have not been updated are particularly vulnerable. The lack of known exploits in the wild currently reduces immediate risk, but the medium severity score and potential for privilege escalation make this a concern for defenders. Organizations failing to address this vulnerability may face increased risk of insider threats or post-compromise escalation by attackers who have gained initial footholds through other means.

1. Upgrade affected systems from Windows 10 Version 1507 to a supported and fully patched version of Windows 10 or later, as this is the most effective mitigation. 2. If upgrading is not immediately possible, restrict local access to affected systems by enforcing strict access controls and limiting administrative privileges to trusted personnel only. 3. Implement application whitelisting and endpoint protection solutions that can detect and block suspicious activities related to privilege escalation attempts targeting the firewall service. 4. Monitor system and security logs for unusual behavior or privilege escalation indicators, particularly related to the Windows Defender Firewall Service. 5. Disable or restrict unnecessary services and firewall rules that could be exploited in conjunction with this vulnerability. 6. Employ network segmentation to limit the impact of compromised systems and reduce lateral movement opportunities. 7. Stay informed on vendor advisories for any forthcoming patches or updates addressing this vulnerability and apply them promptly once available. 8. Conduct regular security audits and vulnerability assessments focusing on legacy systems to identify and remediate similar risks proactively.