Two newly disclosed vulnerabilities in Microsoft’s BitLocker drive encryption feature could allow attackers to bypass encryption safeguards on Windows systems.
Tracked as CVE-2025-55333 and CVE-2025-55338, these flaws involve incomplete comparison logic and configuration weaknesses that may let a local, low-privileged user undermine BitLocker’s protection.
BitLocker is designed to protect data at rest by encrypting entire volumes and requiring authentication factors (such as TPM keys or PINs) before unlocking. Both CVEs target the component that validates encryption policy and key usage rules.
| CVE ID | Description | Released | Severity |
| CVE-2025-55333 | Incomplete comparison with missing factors | Oct 14, 2025 | Important |
| CVE-2025-55338 | Security feature bypass via policy check bypass | Oct 14, 2025 | Important |
By exploiting missing factor checks, an attacker who already has limited code execution on the device could trick BitLocker into treating an unauthorised request as legitimate, thereby decrypting volumes or exposing encryption keys without needing proper credentials.
CVE-2025-55333 stems from an incomplete comparison with missing factors in policy evaluation code.
The vulnerable logic fails to verify all required attributes before approving a decryption request. CVE-2025-55338 shares the same bypass vector string in the Microsoft-published advisory, indicating that similar policy checks are insufficient when handling certain command arguments.
Both vulnerabilities carry an Important severity rating with a CVSS v3.1 base score of 6.1 for network-adjacent attacks and 5.3 for local attacks, reflecting moderate exploit complexity but high potential impact on data confidentiality and integrity.
Microsoft assigned both flaws to its internal CNA and released patches on October 14, 2025. Administrators are urged to apply the October cumulative security update immediately.
The patch corrects the comparison logic by enforcing complete factor validation and updating BitLocker’s command-handling routines to reject malformed requests.
Until updates are applied, organisations should restrict local account creation and remove unnecessary BitLocker administrative privileges.
Additionally, monitoring for unusual BitLocker command executions and operating system logs may help detect attempted bypass attempts.
Ensure all Windows installations with BitLocker enabled are updated with the October patch. Review Group Policy settings to confirm that BitLocker authentication factors, including TPM, PIN, and startup keys, are strictly enforced.
Limit local user privileges to prevent untrusted accounts from running BitLocker management tools. Finally, incorporate these new CVEs into vulnerability scanning workflows to verify remediation across your environment.
Windows BitLocker remains a robust encryption solution when properly configured and patched.
However, these flaws demonstrate that even mature security features require continuous review and timely updates to stay ahead of emerging bypass techniques.
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