New Exploit Allows Attackers to Circumvent Windows BitLocker Security

Microsoft has disclosed a critical vulnerability in Windows BitLocker that allows attackers with physical access to bypass the encryption feature designed to protect sensitive data.

The security flaw, designated as CVE-2025-48818, was publicly announced on July 8, 2025, and affects multiple versions of Windows operating systems, including Windows 10, Windows 11, and Windows Server editions.

Technical Details

The vulnerability stems from a time-of-check time-of-use (TOCTOU) race condition, a timing-based security flaw that occurs when there’s a gap between checking a condition and acting upon it.

This specific weakness, classified under CWE-367, allows unauthorized attackers to exploit the timing window in BitLocker’s security mechanisms.

According to Microsoft’s security advisory, the vulnerability has been assigned a CVSS score of 6.8 out of 10, with a temporal score of 5.9, indicating an “Important” severity level.

The attack vector is classified as physical, meaning attackers must have direct access to the target device.

However, the attack complexity is rated as low, requiring no special privileges or user interaction, making it relatively straightforward for skilled attackers to exploit.

The vulnerability targets explicitly the BitLocker Device Encryption feature, designed to protect data on system storage devices through full-disk encryption.

The TOCTOU race condition allows attackers to circumvent this protection mechanism, potentially gaining unauthorized access to encrypted data that should otherwise remain secure.

Impact and Remediation

The security researchers who discovered this vulnerability, Alon Leviev and Netanel Ben Simon from Microsoft’s Offensive Research & Security Engineering (MORSE) team, have confirmed that successful exploitation could completely bypass BitLocker’s encryption protections.

This represents a significant security risk for organizations and individuals who rely on BitLocker to protect sensitive information stored on their devices.

Microsoft has released security updates for all affected platforms, including Windows 10 for 32-bit systems, Windows 11 versions 23H2 and 24H2 for both x64 and ARM64 architectures, Windows Server 2022, and Windows Server 2025.

The updates are available through various Microsoft security bulletins, with build numbers ranging from 10.0.10240.21073 for older Windows 10 systems to 10.0.26100.4652 for newer Windows 11 and Server 2025 installations.

Currently, there is no evidence of public disclosure of exploit code or active exploitation in the wild.

Microsoft’s exploitability assessment indicates that exploitation is “More Likely,” emphasizing the importance of applying the available security updates promptly.

Organizations should prioritize patching systems that may be exposed to physical access threats, particularly laptops and mobile devices used by remote workers.