CVE-2025-48813 is a vulnerability classified under CWE-324, which pertains to the use of cryptographic keys beyond their expiration date. Specifically, this issue affects Microsoft Windows 11 Version 25H2 (build 10.0.26200.0), where Virtual Secure Mode (VSM) improperly accepts keys that have expired. VSM is a security feature designed to isolate sensitive processes and data from the rest of the operating system, leveraging hardware virtualization to protect cryptographic keys and other secrets. The vulnerability allows an authorized local attacker with low privileges to exploit the acceptance of expired keys to perform spoofing attacks. Spoofing in this context means the attacker can impersonate trusted components or processes by leveraging cryptographic keys that should no longer be valid, potentially bypassing security controls that rely on key validity. The CVSS v3.1 base score is 6.3 (medium severity), reflecting that the attack vector is local (AV:L), requires high attack complexity (AC:H), low privileges (PR:L), and no user interaction (UI:N). The impact on confidentiality and integrity is high (C:H/I:H), but availability is not affected (A:N). No known exploits are currently reported in the wild, and no patches have been linked yet, indicating that mitigation relies on vendor updates and defensive measures. The vulnerability was reserved in May 2025 and published in October 2025, showing a relatively recent discovery. The flaw highlights the importance of proper cryptographic key lifecycle management within secure environments like VSM to prevent misuse of expired credentials.

For European organizations, this vulnerability poses a risk primarily to confidentiality and integrity of sensitive data and operations protected by Virtual Secure Mode on Windows 11 25H2 systems. Attackers with local access could impersonate trusted system components or escalate privileges by exploiting expired keys, potentially leading to unauthorized access to protected secrets or bypassing security mechanisms. This could affect sectors handling sensitive personal data (e.g., finance, healthcare), critical infrastructure, and government systems that rely on Windows 11 25H2 with VSM enabled. Although exploitation requires local access and is complex, insider threats or attackers who have gained initial footholds could leverage this vulnerability to deepen their control or evade detection. The absence of availability impact means systems remain operational but potentially compromised in trustworthiness. The medium severity suggests a moderate but significant risk, especially in environments where strict cryptographic protections are essential. European organizations must be vigilant in monitoring local privilege escalations and cryptographic anomalies to mitigate potential exploitation.

1. Apply official Microsoft patches promptly once released for Windows 11 Version 25H2 to address the expired key acceptance issue in VSM. 2. Enforce strict cryptographic key lifecycle policies, ensuring keys are revoked and removed immediately upon expiration to prevent reuse. 3. Monitor and audit local system activities for unusual cryptographic operations or attempts to use expired keys, leveraging endpoint detection and response (EDR) tools with capabilities to detect anomalies in VSM-related processes. 4. Limit local access to systems running Windows 11 25H2 with VSM enabled by enforcing strong access controls and minimizing the number of users with local privileges. 5. Employ application whitelisting and integrity monitoring to detect unauthorized modifications or spoofing attempts of trusted components. 6. Educate system administrators and security teams about the risks of key misuse and the importance of timely patching and key management. 7. Consider deploying additional hardware-based security modules or trusted platform modules (TPMs) that enforce stricter key validation policies beyond software controls. 8. Regularly review and update security configurations related to VSM and cryptographic services to align with best practices and vendor recommendations.