CVE-2025-55338 is a security feature bypass vulnerability identified in Microsoft Windows 11 Version 25H2, specifically affecting the BitLocker encryption feature. The root cause is the missing ability to patch the ROM code that BitLocker relies on, which is a critical component in enforcing encryption and security policies at the hardware level. Because the ROM code cannot be updated or patched, an attacker with physical access to the device can exploit this flaw to bypass BitLocker's security protections. This bypass could allow unauthorized access to encrypted volumes or the circumvention of encryption enforcement, compromising the confidentiality and integrity of protected data. The vulnerability does not require any user interaction or prior authentication, but it does require physical access to the affected device, which limits the attack vector to scenarios such as theft or insider threats. The CVSS 3.1 base score is 6.1, indicating medium severity, with the vector string AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N, meaning physical attack vector, low attack complexity, no privileges or user interaction required, unchanged scope, and high impact on confidentiality and integrity but no impact on availability. Currently, there are no known exploits in the wild, and no official patches have been released, which means organizations must rely on compensating controls. The vulnerability is categorized under CWE-288 (Authentication Bypass by Alternate Path or Channel), highlighting that the attacker can circumvent authentication mechanisms through an alternate method. This vulnerability is particularly concerning for environments where BitLocker is used to protect sensitive data on Windows 11 devices, as it undermines the trust in hardware-based encryption enforcement.

For European organizations, the impact of CVE-2025-55338 can be significant, especially for sectors that rely heavily on BitLocker for data protection, such as finance, healthcare, government, and critical infrastructure. The ability to bypass BitLocker security features could lead to unauthorized data disclosure, intellectual property theft, or exposure of personal data protected under GDPR, resulting in regulatory penalties and reputational damage. Since the attack requires physical access, organizations with less stringent physical security controls or those with mobile devices at risk of theft are particularly vulnerable. The integrity of encrypted data could also be compromised, potentially allowing attackers to manipulate or tamper with sensitive information. Although availability is not affected, the breach of confidentiality and integrity can disrupt business operations and trust. The lack of a patch means organizations must rely on physical security and monitoring to mitigate risk, which may not be sufficient in all cases. The threat also raises concerns for organizations implementing zero-trust models that assume hardware-based encryption as a security foundation. Overall, the vulnerability could weaken the security posture of European organizations using Windows 11 25H2 with BitLocker, necessitating immediate attention to physical security and incident response readiness.

1. Enhance physical security controls: Restrict physical access to devices, especially laptops and portable devices using BitLocker, through locked rooms, secure storage, and access logging. 2. Implement tamper-evident seals and intrusion detection mechanisms on hardware to detect unauthorized physical access attempts. 3. Use full disk encryption solutions that support firmware or ROM patching capabilities as an alternative until Microsoft releases a patch. 4. Monitor device usage and access patterns for anomalies that could indicate physical tampering or unauthorized access. 5. Educate employees on the risks of device theft and the importance of reporting lost or stolen devices immediately. 6. Maintain up-to-date backups of critical data to enable recovery in case of compromise. 7. Prepare for rapid deployment of Microsoft patches or firmware updates once available by establishing a robust patch management process. 8. Consider additional encryption layers at the application or file level to reduce reliance solely on BitLocker. 9. For high-risk environments, consider hardware security modules or trusted platform modules (TPMs) with enhanced security features that may mitigate this vulnerability. 10. Coordinate with Microsoft support and security advisories to stay informed about updates and recommended actions.