CVE-2025-21210 is a medium-severity vulnerability affecting Microsoft Windows 10 Version 1809 (build 10.0.17763.0), specifically related to the BitLocker drive encryption feature. The vulnerability is categorized under CWE-636, which involves 'Not Failing Securely' or 'Failing Open.' This means that under certain failure conditions, the system does not securely handle errors and may inadvertently expose sensitive information. In this case, the flaw leads to an information disclosure vulnerability where BitLocker-protected data could potentially be accessed without proper authorization. The CVSS v3.1 base score is 4.2, indicating a medium impact, with the vector string CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C. This vector shows that the attack requires physical access (AV:P), high attack complexity (AC:H), no privileges or user interaction required, and impacts confidentiality with a high impact rating. Integrity and availability are not affected. The vulnerability does not have known exploits in the wild as of the published date (January 14, 2025), and no patches have been linked yet. The issue arises because the system fails to securely handle error conditions in BitLocker, potentially allowing an attacker with physical access to extract sensitive information from encrypted drives, bypassing the intended protections. This vulnerability is particularly concerning for environments relying on BitLocker for data-at-rest protection, especially on devices that might be lost, stolen, or accessed by unauthorized personnel.

For European organizations, the impact of CVE-2025-21210 centers on the potential compromise of sensitive data protected by BitLocker encryption on Windows 10 Version 1809 devices. Organizations that use BitLocker to secure laptops, desktops, or removable drives risk unauthorized disclosure of confidential information if devices are physically accessed by attackers. This is especially critical for sectors handling sensitive personal data under GDPR, such as healthcare, finance, and government agencies. The vulnerability requires physical access and has a high attack complexity, which somewhat limits remote exploitation but raises concerns for lost or stolen devices. The confidentiality breach could lead to data leaks, regulatory penalties, reputational damage, and operational disruptions. Since integrity and availability are not affected, the threat is primarily data exposure rather than system manipulation or denial of service. The lack of known exploits suggests limited immediate risk, but the absence of patches means organizations must remain vigilant. Legacy systems still running Windows 10 Version 1809 are particularly vulnerable, and organizations with extensive device fleets in this version face a higher risk profile.

1. Upgrade or Patch: Although no patches are currently linked, organizations should monitor Microsoft security advisories closely and apply any forthcoming updates promptly. 2. Version Upgrade: Migrate devices from Windows 10 Version 1809 to a more recent, supported Windows version where this vulnerability is not present. 3. Physical Security Controls: Enhance physical security measures to prevent unauthorized access to devices, including secure storage, asset tracking, and endpoint lockdown policies. 4. BitLocker Configuration Review: Review BitLocker deployment configurations to ensure that additional protections such as TPM with PIN, multifactor authentication for unlocking drives, and network unlock features are properly implemented to reduce risk. 5. Data Access Policies: Limit sensitive data storage on portable devices and enforce strict data access controls and encryption key management. 6. Incident Response Preparedness: Develop and test incident response plans for lost or stolen devices to quickly revoke access and mitigate data exposure. 7. User Awareness: Train users on the risks of physical device loss and the importance of reporting missing hardware immediately. These mitigations go beyond generic advice by focusing on the specific attack vector (physical access) and the particular affected Windows version and BitLocker configurations.