CVE-2025-53716 is a vulnerability identified in Microsoft Windows 10 Version 1809, specifically affecting build 10.0.17763.0. The issue is a NULL pointer dereference within the Local Security Authority Subsystem Service (LSASS), a critical component responsible for enforcing security policies, handling authentication, and managing user logins. This vulnerability arises when LSASS attempts to access or dereference a pointer that has not been properly initialized or has been set to NULL, leading to a system crash or denial of service (DoS). The vulnerability requires an attacker with authorized access privileges to exploit, meaning the attacker must have some level of legitimate access to the targeted system or network. Exploitation does not require user interaction and can be performed remotely over the network, making it a network-based DoS vector. The CVSS v3.1 base score is 6.5, indicating a medium severity level, with the attack vector being network (AV:N), low attack complexity (AC:L), requiring privileges (PR:L), no user interaction (UI:N), and impacting availability only (A:H) without affecting confidentiality or integrity. No known exploits are currently reported in the wild, and no patches or mitigations have been linked yet. The vulnerability falls under CWE-476 (NULL Pointer Dereference), a common programming error that can lead to application crashes or system instability. Given the critical role of LSASS in Windows security, exploitation can cause system unavailability, potentially disrupting authentication services and access to resources on affected machines.

For European organizations, this vulnerability could lead to significant operational disruptions, especially in environments where Windows 10 Version 1809 is still in use. The denial of service caused by LSASS crashing can result in system reboots or service outages, impacting user authentication and access to network resources. This could affect enterprise environments, government agencies, and critical infrastructure sectors relying on Windows 10 endpoints for daily operations. While the vulnerability does not allow data theft or privilege escalation, the loss of availability can interrupt business continuity, delay critical processes, and increase helpdesk workload. Organizations with remote access services or those exposing LSASS-related services over the network are particularly at risk. The requirement for attacker privileges limits the attack surface somewhat, but insider threats or compromised accounts could be leveraged to exploit this vulnerability. Additionally, legacy systems or those not updated to newer Windows versions remain vulnerable, increasing the risk in sectors with slower patch cycles or strict change management policies.

Given the absence of an official patch at this time, European organizations should implement several targeted mitigations: 1) Restrict network access to LSASS-related services using network segmentation and firewall rules to limit exposure only to trusted hosts and users. 2) Enforce strict privilege management and monitoring to reduce the risk of authorized users misusing their access or compromised credentials being exploited. 3) Deploy endpoint detection and response (EDR) solutions capable of detecting abnormal LSASS crashes or suspicious network activity targeting authentication services. 4) Encourage migration or upgrade from Windows 10 Version 1809 to supported, patched Windows versions where this vulnerability is resolved. 5) Implement robust incident response plans to quickly identify and recover from denial of service events impacting authentication services. 6) Monitor security advisories from Microsoft for updates or patches related to CVE-2025-53716 and apply them promptly once available.