CVE-2025-53810 is a vulnerability classified under CWE-843, which involves 'Access of Resource Using Incompatible Type,' commonly known as a type confusion flaw. This specific vulnerability affects the Windows Defender Firewall Service on Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The flaw allows an authorized local attacker—meaning the attacker must have some level of access to the system—to exploit the type confusion issue to elevate their privileges on the affected system. Type confusion vulnerabilities occur when a program mistakenly treats a piece of memory as a different data type than it actually is, which can lead to unexpected behavior, including arbitrary code execution or escalation of privileges. In this case, the attacker can leverage this flaw to gain higher privileges than originally granted, potentially allowing them to execute code with SYSTEM-level permissions or modify critical system components. The vulnerability has a CVSS v3.1 base score of 6.7, indicating a medium severity level. The vector details specify that the attack requires local access (AV:L), low attack complexity (AC:L), and high privileges (PR:H) but no user interaction (UI:N). The impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H), meaning the attacker can fully compromise the system. No known exploits are currently reported in the wild, and no official patches or mitigation links have been provided yet. The vulnerability was reserved in July 2025 and published in September 2025, indicating it is a recent discovery. Given that Windows 10 Version 1809 is an older release (initially launched in late 2018), many organizations may have already moved to newer versions, but legacy systems and certain industrial or embedded environments may still be running this version, making them vulnerable.

For European organizations, the impact of CVE-2025-53810 can be significant, especially for those still operating legacy Windows 10 Version 1809 systems. Successful exploitation allows an attacker with local access and some privileges to escalate to SYSTEM-level privileges, potentially leading to full system compromise. This can result in unauthorized access to sensitive data, disruption of critical services, and the ability to deploy malware or ransomware with elevated rights. Sectors such as finance, healthcare, manufacturing, and government agencies in Europe often have legacy systems or specialized environments where upgrading is slow, increasing their exposure. Additionally, the high impact on confidentiality, integrity, and availability means that data breaches, operational disruptions, and compliance violations (e.g., GDPR) could occur. Although no public exploits are known yet, the medium severity and ease of exploitation (low complexity) suggest that threat actors could develop exploits in the near future, increasing risk. Organizations relying on Windows Defender Firewall Service for network security could see their perimeter defenses bypassed or manipulated if attackers gain elevated privileges. The lack of a patch at the time of publication further exacerbates the risk, requiring organizations to implement interim mitigations.

1. Upgrade and Patch: The most effective mitigation is to upgrade affected systems to a supported and fully patched version of Windows 10 or later, as Windows 10 Version 1809 is out of mainstream support and unlikely to receive security patches. 2. Restrict Local Access: Limit local access to systems running Windows 10 Version 1809 by enforcing strict access controls, using network segmentation, and applying the principle of least privilege to reduce the number of users who can log in locally. 3. Application Whitelisting and Endpoint Protection: Deploy application whitelisting and advanced endpoint detection and response (EDR) solutions to detect and block suspicious activities that may indicate exploitation attempts. 4. Monitor and Audit: Enable detailed logging and monitoring of Windows Defender Firewall Service and privilege escalation attempts. Use Security Information and Event Management (SIEM) tools to alert on anomalous behavior. 5. Disable or Harden Windows Defender Firewall Service: If feasible, temporarily disable or restrict the Windows Defender Firewall Service on vulnerable systems or apply configuration hardening to reduce the attack surface until patches are available. 6. User Training and Awareness: Educate users about the risks of local privilege escalation and enforce policies to prevent unauthorized software installation or execution. 7. Incident Response Preparedness: Prepare incident response plans specifically addressing privilege escalation attacks and ensure backups and recovery procedures are tested and up to date.