CVE-2025-55338 is a vulnerability identified in Microsoft Windows 11 Version 25H2 (build 10.0.26200.0) that affects the BitLocker encryption feature. The root cause is the missing ability to patch ROM code related to BitLocker, which leads to a security feature bypass. BitLocker is designed to protect data confidentiality and integrity by encrypting volumes and preventing unauthorized access. However, this vulnerability allows an attacker with physical access to the device to bypass BitLocker protections without requiring any privileges or user interaction. The attack vector is physical, meaning the attacker must have direct access to the hardware to exploit the flaw. The vulnerability is classified under CWE-288 (Authentication Bypass Using an Alternate Path or Channel), indicating that the attacker can circumvent security controls by exploiting an alternate mechanism. The CVSS v3.1 score is 6.1, reflecting medium severity, with high impact on confidentiality and integrity but no impact on availability. No known exploits have been reported in the wild, and no official patches have been released at the time of publication. The inability to patch ROM code suggests that firmware-level protections are insufficient or immutable, complicating remediation. This vulnerability poses a significant risk to organizations relying on BitLocker for data protection, especially in environments where devices may be physically accessible to attackers. The lack of user interaction and privileges required makes it a stealthy and potentially effective attack vector once physical access is gained.

For European organizations, the impact of CVE-2025-55338 is primarily on the confidentiality and integrity of sensitive data protected by BitLocker encryption on Windows 11 Version 25H2 devices. If exploited, attackers can bypass BitLocker protections, potentially leading to unauthorized data disclosure or tampering. This is particularly critical for sectors handling sensitive personal data (e.g., GDPR-regulated entities), intellectual property, or critical infrastructure information. The physical attack requirement limits the scope to scenarios where devices are lost, stolen, or physically accessed by malicious insiders or attackers. However, given the widespread adoption of Windows 11 in Europe and the common use of BitLocker for endpoint encryption, the vulnerability could facilitate data breaches, regulatory non-compliance, and reputational damage. Organizations with remote or mobile workforces, or those with less stringent physical security controls, face higher risks. The inability to patch ROM code complicates mitigation and prolongs exposure until firmware or hardware-level fixes are developed and deployed. This vulnerability could also undermine trust in BitLocker as a secure encryption solution, impacting broader cybersecurity postures across European enterprises.

1. Enhance physical security controls to prevent unauthorized access to devices, including secure storage, access logging, and surveillance. 2. Implement strict device handling policies, especially for laptops and portable devices using BitLocker encryption. 3. Use hardware-based security modules (e.g., TPM) with updated firmware where possible, and monitor vendor advisories for firmware updates addressing ROM patching capabilities. 4. Employ multi-factor authentication and strong pre-boot authentication mechanisms to add layers beyond BitLocker encryption. 5. Restrict administrative privileges and monitor for unusual device access or tampering attempts. 6. Prepare for deployment of official patches or firmware updates from Microsoft and hardware vendors as soon as they become available. 7. Conduct regular security awareness training emphasizing the risks of physical device compromise. 8. Consider additional encryption or data protection solutions that do not rely solely on BitLocker ROM code. 9. Maintain an incident response plan that includes procedures for potential physical compromise scenarios. 10. Audit and inventory all devices running Windows 11 Version 25H2 with BitLocker enabled to prioritize risk management efforts.