CVE-2025-21213 is a vulnerability identified in Microsoft Windows 10 Version 1507 (build 10.0.10240.0) that allows an attacker to bypass the Secure Boot security feature due to improper access control, classified under CWE-284. Secure Boot is a critical security mechanism designed to ensure that only trusted software is loaded during the system boot process, protecting against rootkits and bootkits. This vulnerability arises because the access control mechanisms governing Secure Boot enforcement are flawed, allowing an attacker with physical access to circumvent these protections without requiring any privileges or user interaction. The CVSS v3.1 base score is 4.6 (medium severity), with an attack vector of physical access (AV:P), low attack complexity (AC:L), no privileges required (PR:N), and no user interaction (UI:N). The impact primarily affects confidentiality, as unauthorized code could be executed during boot, potentially exposing sensitive information or enabling persistent malware. However, integrity and availability impacts are not indicated. No known exploits have been reported in the wild, and no official patches have been released as of the publication date (January 14, 2025). The vulnerability is specific to the earliest Windows 10 release (Version 1507), which is largely out of mainstream support but may still be in use in legacy environments. The improper access control weakness suggests that Secure Boot enforcement can be bypassed, undermining the trustworthiness of the boot process and potentially allowing attackers to load unsigned or malicious bootloaders or OS loaders.

For European organizations, the primary impact of CVE-2025-21213 lies in the potential compromise of system confidentiality and the security of the boot process. Organizations relying on legacy Windows 10 Version 1507 systems, particularly in sectors such as government, critical infrastructure, finance, and healthcare, could face risks of persistent malware infections that evade detection by traditional security controls. The ability to bypass Secure Boot may allow attackers to implant rootkits or bootkits that persist across reboots and evade antivirus solutions, leading to long-term espionage or data exfiltration. Although the attack requires physical access, insider threats or attackers with temporary physical access (e.g., during maintenance or at shared facilities) could exploit this vulnerability. The lack of integrity and availability impacts reduces the risk of direct system disruption or data tampering, but the confidentiality breach potential remains significant. Since Windows 10 Version 1507 is an outdated release, the impact is mitigated by the decreasing number of affected systems; however, legacy systems in industrial control environments or specialized devices may still be vulnerable. The absence of known exploits in the wild lowers immediate risk but does not preclude future exploitation once proof-of-concept code becomes available.

To mitigate CVE-2025-21213, European organizations should prioritize upgrading all affected Windows 10 Version 1507 systems to a supported and patched Windows version with enhanced Secure Boot implementations. Given that no patches are currently available for this specific vulnerability, migration away from the vulnerable OS version is the most effective measure. Organizations should enforce strict physical security controls to prevent unauthorized access to devices, including locked server rooms, restricted access to endpoints, and surveillance in sensitive areas. Implementing hardware-based security features such as TPM (Trusted Platform Module) and ensuring Secure Boot is enabled and properly configured can reduce risk. Regular audits of device firmware and boot configurations should be conducted to detect unauthorized changes. Additionally, organizations should maintain up-to-date endpoint detection and response (EDR) solutions capable of identifying boot-level malware and monitor for unusual system behavior indicative of boot process compromise. Employee training to recognize insider threat risks and secure handling of devices is also recommended. Finally, organizations should stay alert for official patches or advisories from Microsoft and apply them promptly once available.