CVE-2025-54894 is a heap-based buffer overflow vulnerability classified under CWE-122, affecting the Local Security Authority Subsystem Service (LSASS) in 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 logins. The vulnerability arises from improper handling of heap memory within LSASS, allowing a local attacker with limited privileges to trigger a buffer overflow condition. This overflow can overwrite adjacent memory, potentially enabling arbitrary code execution with elevated privileges. The attack vector requires local access with low privileges and no user interaction, making it a potent elevation of privilege vulnerability. The CVSS v3.1 base score is 7.8, indicating high severity due to high impact on confidentiality, integrity, and availability, combined with relatively low attack complexity and no user interaction needed. Although no exploits are currently known in the wild, the vulnerability poses a significant risk to systems that remain unpatched or unsupported. The absence of an official patch at the time of publication increases the urgency for organizations to implement compensating controls. This vulnerability is particularly dangerous because it targets LSASS, a core security process, and successful exploitation could lead to full system compromise, including unauthorized access to sensitive data and disruption of system operations.

For European organizations, the impact of CVE-2025-54894 could be severe. Exploitation allows attackers to elevate privileges locally, potentially gaining SYSTEM-level access. This could lead to unauthorized access to sensitive information, disruption of critical services, and the ability to deploy further malware or ransomware. Organizations relying on Windows 10 Version 1809, especially those in sectors such as finance, healthcare, government, and critical infrastructure, face increased risk of data breaches and operational downtime. The vulnerability undermines the integrity of authentication mechanisms, potentially allowing attackers to bypass security controls. Given the high confidentiality, integrity, and availability impact, exploitation could result in significant regulatory and compliance consequences under GDPR and other European data protection laws. The lack of known exploits currently provides a window for proactive defense, but delayed patching or continued use of legacy systems could expose organizations to future attacks once exploit code becomes available.

1. Prioritize upgrading or patching Windows 10 systems to versions later than 1809 where this vulnerability is fixed once patches are released. 2. Until patches are available, restrict local access to systems running Windows 10 Version 1809 by enforcing strict access controls and limiting user privileges. 3. Employ application whitelisting and endpoint detection and response (EDR) solutions to monitor and block suspicious LSASS process behavior and memory anomalies. 4. Implement network segmentation to isolate critical systems and reduce the attack surface for local privilege escalation attempts. 5. Regularly audit and review user accounts and permissions to minimize the number of users with local access rights. 6. Use enhanced logging and alerting on LSASS-related events to detect potential exploitation attempts early. 7. Educate IT staff and users about the risks of running outdated OS versions and the importance of timely updates. 8. Consider deploying host-based intrusion prevention systems (HIPS) that can detect heap overflow patterns targeting LSASS. 9. Maintain offline backups and incident response plans to quickly recover from potential compromises.