CVE-2025-48810 is a medium-severity vulnerability affecting Microsoft Windows Server 2025, specifically the Server Core installation version 10.0.26100.0. The vulnerability arises from processor optimization that removes or modifies security-critical code within the Windows Secure Kernel Mode. This kernel mode is a highly privileged execution environment designed to enforce security boundaries and protect sensitive system operations. The optimization inadvertently compromises the integrity of security-critical code, allowing an authorized attacker with local access and low privileges (PR:L) to disclose sensitive information without requiring user interaction (UI:N). The vulnerability does not impact system integrity or availability but has a high impact on confidentiality (C:H). The attack vector is local, requiring the attacker to have some level of access to the system, but no elevated privileges beyond authorized user rights are necessary. The vulnerability is classified under CWE-1037, which relates to the removal or modification of security-critical code due to processor optimizations. No known exploits are currently in the wild, and no patches have been published yet. The CVSS v3.1 base score is 5.5, reflecting a medium severity level. This vulnerability highlights the risks associated with aggressive processor optimizations that may unintentionally bypass or weaken security mechanisms embedded in kernel code, especially in hardened environments like Server Core installations that are often used in enterprise and data center contexts.

For European organizations, this vulnerability poses a risk primarily to confidentiality of sensitive data processed or stored on Windows Server 2025 Server Core installations. Since Server Core is commonly deployed in data centers and cloud infrastructure for critical services due to its minimal footprint and reduced attack surface, an attacker with local access could leverage this vulnerability to extract sensitive information, such as cryptographic keys, credentials, or other protected data from the Secure Kernel Mode. Although exploitation requires local access, insider threats or attackers who gain foothold through other means (e.g., compromised accounts, lateral movement) could escalate their information gathering capabilities. This could lead to data breaches, intellectual property theft, or exposure of personal data subject to GDPR regulations, potentially resulting in regulatory fines and reputational damage. The lack of impact on integrity and availability means system operations remain intact, but confidentiality breaches alone can have severe consequences in sectors like finance, healthcare, and government. The absence of known exploits currently provides a window for proactive mitigation, but organizations should prioritize patching once updates become available. The Server Core installation's usage in European enterprises and cloud providers makes this vulnerability relevant for a broad range of industries.

1. Restrict local access strictly: Limit the number of users with local login rights on Windows Server 2025 Server Core installations to only essential personnel. 2. Implement strong access controls and monitoring: Use endpoint detection and response (EDR) tools to monitor for suspicious local activity that could indicate attempts to exploit this vulnerability. 3. Apply principle of least privilege: Ensure users and services operate with the minimum privileges necessary to reduce the risk of authorized attackers exploiting the vulnerability. 4. Harden server configurations: Disable unnecessary services and interfaces that could provide local access vectors. 5. Maintain up-to-date system inventories: Identify all Windows Server 2025 Server Core installations to prioritize patch management once Microsoft releases a security update. 6. Use virtualization and isolation: Deploy critical workloads in isolated virtual environments to contain potential breaches. 7. Prepare incident response plans: Develop procedures for rapid detection and containment of local privilege escalation or information disclosure incidents. 8. Engage with Microsoft support: Monitor official Microsoft channels for patches or workarounds and apply them promptly upon release. These steps go beyond generic advice by focusing on minimizing local access, monitoring for exploitation attempts, and preparing for rapid response, which are critical given the local attack vector and confidentiality impact.