CVE-2026-20941 is a vulnerability classified under CWE-59 (Improper Link Resolution Before File Access) affecting Microsoft Windows Server 2025, specifically the Server Core installation version 10.0.26100.0. The flaw resides in the Host Process for Windows Tasks, where the system improperly resolves symbolic links or junction points before accessing files. This improper link following can be exploited by an authorized local attacker to escalate privileges on the system. The attacker must have some level of local privileges but does not require user interaction to exploit the vulnerability. The CVSS v3.1 base score is 7.8, indicating high severity, with impacts rated high on confidentiality, integrity, and availability. The attack vector is local (AV:L), with low attack complexity (AC:L), requiring privileges (PR:L), no user interaction (UI:N), and unchanged scope (S:U). The vulnerability allows an attacker to manipulate file system links to gain elevated privileges, potentially leading to full system compromise. No public exploits or patches are currently available, but the vulnerability has been officially published and reserved since December 2025. The Server Core installation is commonly used in enterprise and data center environments due to its reduced footprint and attack surface, making this vulnerability particularly concerning for critical infrastructure and cloud service providers. The improper link resolution issue could be leveraged to bypass security controls and execute arbitrary code with elevated privileges, threatening system stability and security.

For European organizations, the impact of CVE-2026-20941 is significant due to the widespread use of Microsoft Windows Server in enterprise, government, and critical infrastructure sectors. Successful exploitation could allow attackers to escalate privileges locally, potentially leading to full system compromise, data breaches, and disruption of services. This is especially critical for organizations relying on Server Core installations for their reduced attack surface and performance benefits, as this vulnerability undermines those security assumptions. The compromise of servers in sectors such as finance, healthcare, energy, and public administration could result in severe confidentiality, integrity, and availability losses. Additionally, the ability to escalate privileges without user interaction increases the risk of automated or stealthy attacks within internal networks. Although no known exploits are currently in the wild, the high CVSS score and nature of the vulnerability suggest that threat actors may develop exploits, increasing the urgency for mitigation. The impact extends to cloud service providers and managed service providers in Europe who host or manage Windows Server 2025 environments, potentially affecting multiple downstream customers.

1. Monitor Microsoft security advisories closely and apply official patches or updates as soon as they become available for Windows Server 2025 (Server Core installation). 2. Restrict local access to Windows Server 2025 systems to trusted administrators only, minimizing the number of users with privileges that could exploit this vulnerability. 3. Implement strict access control policies and use role-based access control (RBAC) to limit privilege levels for users and processes. 4. Employ application whitelisting and endpoint detection and response (EDR) solutions to detect anomalous behavior related to file system link manipulation or privilege escalation attempts. 5. Conduct regular audits of symbolic links and junction points on critical servers to identify and remediate any suspicious or unauthorized link configurations. 6. Use virtualization or containerization isolation techniques where possible to limit the impact of potential privilege escalations. 7. Harden server configurations by disabling unnecessary services and features that could be leveraged in conjunction with this vulnerability. 8. Educate system administrators about the risks of improper link resolution and encourage vigilance in monitoring system logs for unusual activity related to the Host Process for Windows Tasks. 9. Prepare incident response plans that include scenarios involving local privilege escalation to ensure rapid containment and remediation if exploitation occurs.