CVE-2025-48813 is a vulnerability identified in Microsoft Windows 11 Version 25H2 (build 10.0.26200.0) that involves the use of cryptographic keys beyond their expiration date within the Virtual Secure Mode (VSM) environment. VSM is a security feature that isolates sensitive processes and data using hardware virtualization and secure enclaves to protect against kernel-level exploits. The vulnerability is classified under CWE-324, which pertains to the use of cryptographic keys past their validity period. When keys are used after expiration, cryptographic assurances weaken, enabling attackers to spoof identities or processes. In this case, an attacker with low privileges but local access can exploit the expired key usage to perform spoofing attacks, potentially impersonating trusted components or processes within the VSM. This could lead to unauthorized access to sensitive information or manipulation of system behavior, compromising confidentiality and integrity. The CVSS 3.1 base score is 6.3, indicating medium severity, with attack vector local (AV:L), attack complexity high (AC:H), privileges required low (PR:L), no user interaction (UI:N), unchanged scope (S:U), and high impact on confidentiality and integrity (C:H/I:H), but no impact on availability (A:N). No known exploits have been reported in the wild, and no patches have been published at the time of disclosure. The vulnerability was reserved in May 2025 and published in October 2025. The lack of patches means organizations must rely on compensating controls until updates are available.

For European organizations, the exploitation of CVE-2025-48813 could lead to significant confidentiality and integrity breaches within Windows 11 systems employing VSM. Spoofing attacks could allow attackers to impersonate trusted system components or users, potentially enabling unauthorized data access, privilege escalation, or manipulation of security controls. This is particularly critical for sectors handling sensitive personal data (e.g., finance, healthcare, government) due to GDPR compliance requirements. The requirement for local access limits remote exploitation but increases risk from insider threats or attackers who have already gained foothold via other means. The absence of availability impact reduces the likelihood of service disruption but does not diminish the risk of stealthy data compromise. Given the widespread adoption of Windows 11 in enterprise environments across Europe, the vulnerability poses a moderate risk to organizational security postures until mitigated.

1. Implement strict key lifecycle management policies to ensure cryptographic keys are rotated and invalidated promptly before expiration. 2. Monitor and audit Virtual Secure Mode operations and cryptographic key usage logs to detect anomalies indicative of expired key usage or spoofing attempts. 3. Restrict local access to systems running Windows 11 25H2 to trusted personnel only, employing strong access controls and endpoint security solutions. 4. Employ application whitelisting and integrity verification mechanisms to detect unauthorized process impersonation. 5. Prepare for rapid deployment of Microsoft patches once released by maintaining up-to-date asset inventories and patch management workflows. 6. Conduct internal security awareness training focusing on insider threat risks and the importance of reporting suspicious system behavior. 7. Consider deploying additional endpoint detection and response (EDR) tools capable of identifying unusual cryptographic operations or privilege escalations related to VSM.