CVE-2025-53716 is a null pointer dereference vulnerability classified under CWE-476, found in the Local Security Authority Subsystem Service (LSASS) of Microsoft Windows 10 Version 1809 (build 10.0.17763.0). LSASS is a critical Windows component responsible for enforcing security policies, handling authentication, and managing user credentials. The vulnerability allows an authorized attacker with network access and low privileges to send specially crafted requests to LSASS, causing it to dereference a null pointer. This results in a denial of service (DoS) by crashing or destabilizing the LSASS process, which can lead to system instability or forced reboot. The CVSS v3.1 base score is 6.5 (medium), reflecting network attack vector (AV:N), low attack complexity (AC:L), required privileges (PR:L), no user interaction (UI:N), unchanged scope (S:U), no impact on confidentiality or integrity (C:N/I:N), but high impact on availability (A:H). No known exploits have been reported in the wild, and no official patches have been released as of the publication date. The vulnerability primarily affects legacy Windows 10 installations, which may still be operational in some enterprise environments. The lack of patches and the critical role of LSASS mean that exploitation could disrupt authentication services and potentially cause downtime in affected systems.

For European organizations, the primary impact of CVE-2025-53716 is denial of service, which can disrupt authentication and security services managed by LSASS. This can lead to system crashes, forced reboots, and temporary loss of access to critical services, impacting business continuity. Organizations running Windows 10 Version 1809 in production environments, especially in sectors like finance, healthcare, government, and critical infrastructure, may experience operational disruptions. The vulnerability does not expose sensitive data or allow privilege escalation, but availability interruptions can cause significant operational and reputational damage. Since exploitation requires only low privileges and no user interaction, attackers with network access could leverage this flaw to disrupt services remotely. The absence of known exploits reduces immediate risk, but the lack of patches means the threat remains until mitigated or updated. European entities with legacy systems or slow patch cycles are particularly vulnerable to service outages and potential cascading effects on dependent systems.

1. Upgrade affected systems to a supported and patched version of Windows 10 or later, as Windows 10 Version 1809 is legacy and may no longer receive security updates. 2. Implement strict network segmentation and firewall rules to limit network access to LSASS services, reducing the attack surface. 3. Monitor LSASS process stability and system logs for unusual crashes or service interruptions that could indicate exploitation attempts. 4. Employ intrusion detection and prevention systems (IDS/IPS) tuned to detect anomalous LSASS network traffic patterns. 5. Restrict privileges on accounts that can access LSASS over the network to minimize potential attackers. 6. Develop and test incident response plans for rapid recovery from LSASS-related service disruptions. 7. If immediate upgrade is not feasible, consider temporary workarounds such as disabling unnecessary network services or applying vendor-recommended mitigations when available. 8. Maintain up-to-date backups and system snapshots to enable quick restoration in case of DoS-induced outages.