CVE-2025-55338 is a security feature bypass vulnerability identified in Microsoft Windows 11 Version 25H2 (build 10.0.26200.0) that affects the BitLocker encryption feature. BitLocker relies on firmware and ROM code to secure encryption keys and enforce security policies. This vulnerability arises because the ROM code involved in BitLocker’s operation cannot be patched or updated, creating a persistent attack surface. An attacker with physical access to the device can exploit this flaw to bypass BitLocker protections, potentially gaining unauthorized access to encrypted data or compromising system integrity. The attack does not require any privileges or user interaction, but physical access is mandatory, limiting remote exploitation. The CVSS v3.1 score is 6.1 (medium severity), reflecting high impact on confidentiality and integrity but no impact on availability. No known exploits have been reported in the wild, and no patches have been released, indicating the vulnerability is newly disclosed and under active assessment. The inability to patch ROM code means that traditional software updates cannot remediate the issue, necessitating alternative mitigation strategies. This vulnerability highlights a critical limitation in firmware security for encryption technologies and underscores the importance of physical security controls. Organizations relying on BitLocker for data protection on Windows 11 25H2 devices should evaluate their exposure and implement compensating controls to prevent unauthorized physical access and tampering.

For European organizations, the primary impact of CVE-2025-55338 is the potential compromise of data confidentiality and integrity on devices protected by BitLocker in Windows 11 Version 25H2. This is particularly concerning for sectors handling sensitive or regulated data such as finance, healthcare, government, and critical infrastructure. The vulnerability enables attackers with physical access to bypass encryption safeguards, potentially exposing sensitive information or enabling further system compromise. Although the attack requires physical presence, the widespread use of portable devices in European enterprises increases the risk of theft or unauthorized access. The inability to patch the ROM code means that affected devices remain vulnerable until hardware revisions or firmware updates become available. This could lead to increased risk of data breaches, regulatory non-compliance, and reputational damage. The impact is mitigated somewhat by the lack of remote exploitability and the medium severity rating, but organizations must still consider the risk in their threat models, especially for high-value targets and environments with less stringent physical security.

1. Enforce strict physical security controls to prevent unauthorized access to devices, including secure storage, access logging, and surveillance in sensitive environments. 2. Use hardware security modules (HSMs) or Trusted Platform Modules (TPMs) that support firmware updates and enhanced protection mechanisms where possible. 3. Implement multi-factor authentication and strong pre-boot authentication methods to add layers of security beyond BitLocker. 4. Monitor for signs of physical tampering or device theft and establish rapid incident response procedures. 5. Limit the use of Windows 11 Version 25H2 on devices handling highly sensitive data until patches or hardware fixes are available. 6. Maintain up-to-date asset inventories and conduct regular risk assessments focused on physical security vulnerabilities. 7. Engage with Microsoft and hardware vendors for updates on patches or hardware revisions addressing the ROM code issue. 8. Educate employees on the importance of device security and reporting lost or stolen equipment immediately. 9. Consider alternative encryption solutions or layered encryption approaches that do not rely solely on vulnerable ROM code. 10. Apply all available Windows updates promptly to mitigate other vulnerabilities and reduce overall attack surface.