CVE-2025-29838 is a high-severity vulnerability identified in Microsoft Windows Server 2025, specifically affecting the Server Core installation version 10.0.26100.0. The vulnerability is classified as CWE-476, which corresponds to a NULL Pointer Dereference. This type of flaw occurs when the software attempts to dereference a pointer that has a NULL value, leading to undefined behavior such as crashes or memory corruption. In this case, the issue resides within Windows Drivers, which are critical components that operate at a low level within the operating system. Exploitation of this vulnerability allows an unauthorized local attacker to elevate privileges, potentially gaining higher-level access rights than originally permitted. The CVSS v3.1 base score is 7.4, indicating a high severity level. The vector string (AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H) shows that the attack requires local access (AV:L), high attack complexity (AC:H), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), and impacts confidentiality, integrity, and availability to a high degree (C:H/I:H/A:H). Although no known exploits are reported in the wild yet, the vulnerability poses a significant risk due to its potential to compromise core server functions and elevate privileges without authentication or user interaction. The lack of available patches at the time of publication increases the urgency for organizations to monitor updates closely and implement interim protective measures. The Server Core installation is a minimalistic Windows Server deployment option designed to reduce the attack surface by limiting installed components and GUI elements, but this vulnerability undermines that security benefit by allowing local privilege escalation through driver-level flaws.

For European organizations, this vulnerability could have severe consequences, especially for enterprises and public sector entities relying on Windows Server 2025 Server Core installations for critical infrastructure, cloud services, and internal applications. Successful exploitation could allow attackers to gain administrative privileges locally, enabling them to bypass security controls, install persistent malware, exfiltrate sensitive data, or disrupt services. This is particularly concerning for sectors with stringent data protection requirements such as finance, healthcare, and government, where confidentiality and integrity are paramount. The high impact on availability also raises concerns about potential denial-of-service conditions caused by system crashes or instability. Given the local access requirement, the threat is more relevant to insider threats or attackers who have already compromised a lower-privileged account or gained physical access to servers. However, once privilege escalation is achieved, lateral movement and further compromise within the network become feasible. The lack of user interaction needed for exploitation increases the risk of automated or stealthy attacks. European organizations with hybrid or on-premises deployments of Windows Server 2025 should prioritize assessing their exposure and readiness to respond to this vulnerability.

1. Immediate mitigation should focus on restricting local access to Windows Server 2025 Server Core systems, ensuring that only trusted administrators and processes have login capabilities. 2. Implement strict access controls and monitoring on servers to detect unusual privilege escalation attempts or driver-related errors. 3. Employ application whitelisting and driver signing enforcement to prevent unauthorized or malicious drivers from loading. 4. Use virtualization-based security features and hardware-enforced isolation where available to limit the impact of driver-level vulnerabilities. 5. Regularly audit and harden server configurations, removing unnecessary local accounts and services to reduce attack vectors. 6. Monitor official Microsoft channels for patches or security advisories related to CVE-2025-29838 and apply updates promptly once available. 7. Consider deploying endpoint detection and response (EDR) solutions capable of identifying anomalous behavior indicative of privilege escalation or driver exploitation. 8. Conduct internal penetration testing and vulnerability assessments focusing on privilege escalation paths to validate defenses. These measures go beyond generic advice by emphasizing access restriction, driver integrity, and proactive monitoring tailored to the specific nature of the vulnerability.