CVE-2025-53810 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). This vulnerability allows an attacker with authorized local access and elevated privileges to exploit a type confusion flaw, where the system incorrectly accesses or interprets a resource using an incompatible data type. This can lead to memory corruption, enabling the attacker to escalate privileges further within the system. The vulnerability does not require user interaction but does require the attacker to already have some level of privilege (PR:H in CVSS), indicating that it is a local privilege escalation rather than a remote code execution vector. The CVSS v3.1 base score is 6.7 (medium severity), reflecting the significant impact on confidentiality, integrity, and availability if exploited. No public exploits or proof-of-concept code are currently known, and no official patches have been linked yet, though the vulnerability was published on September 9, 2025. The flaw specifically targets the firewall service, a critical component responsible for network traffic filtering and security, making successful exploitation potentially impactful for system security and stability.

For European organizations, the impact of CVE-2025-53810 can be substantial, particularly for those still operating legacy Windows 10 Version 1809 systems. Successful exploitation could allow attackers with local access to elevate privileges, potentially gaining SYSTEM-level control. This could lead to unauthorized access to sensitive data, disruption of firewall protections, and further lateral movement within networks. Critical infrastructure sectors such as energy, finance, healthcare, and government agencies are especially vulnerable due to their reliance on Windows environments and the critical role of firewall services in their security posture. The vulnerability could undermine network defenses, enabling attackers to bypass security controls and compromise confidentiality, integrity, and availability of systems. Although exploitation requires local access and some privilege, insider threats or attackers who have gained initial footholds could leverage this flaw to deepen their control. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers often develop exploits post-disclosure.

European organizations should prioritize migrating away from Windows 10 Version 1809 to supported and updated Windows versions to eliminate exposure to this vulnerability. Until migration is complete, organizations should apply any available security updates or patches from Microsoft as soon as they are released. Restrict local administrative privileges strictly to trusted personnel and enforce the principle of least privilege to reduce the risk of exploitation. Employ endpoint detection and response (EDR) solutions to monitor for unusual behavior related to the Windows Defender Firewall Service and privilege escalation attempts. Regularly audit local accounts and access permissions to detect unauthorized privilege escalations. Network segmentation and strict access controls can limit the ability of attackers to gain local access to critical systems. Additionally, organizations should maintain up-to-date backups and incident response plans to quickly recover from potential compromises. Monitoring Microsoft security advisories for updates on this vulnerability is essential.