Critical Windows BitLocker Flaw Allows Attackers to Bypass Encryption

Microsoft has disclosed a significant security vulnerability in its BitLocker encryption system that could allow attackers with physical access to bypass device encryption protections.

The vulnerability, designated CVE-2025-48818, was released on July 8, 2025, and has been classified as “Important” severity with a CVSS score of 6.8 out of 10.

Race Condition Flaw Enables Physical Attacks

The newly discovered vulnerability stems from a time-of-check time-of-use (TOCTOU) race condition in Windows BitLocker, a critical weakness that creates a window of opportunity for malicious actors.

This type of security flaw occurs when there’s a gap between when a security check is performed and when the action is executed, allowing attackers to manipulate the system during this brief interval.

According to Microsoft’s security advisory, the vulnerability specifically affects BitLocker Device Encryption, the feature responsible for protecting data stored on system storage devices.

An attacker who successfully exploits this flaw could gain unauthorized access to encrypted data that should otherwise be protected by BitLocker’s security mechanisms.

The attack vector requires physical access to the target device, meaning remote exploitation is not possible.

However, the attack complexity is rated as “low,” and crucially, no special privileges or user interaction are required to exploit the vulnerability.

This combination of factors has led Microsoft to assess that “exploitation is more likely” despite the physical access requirement.

Discovery and Response from Microsoft’s Security Team

The vulnerability was discovered by Microsoft’s security researchers, Alon Leviev and Netanel Ben Simon, who are part of the Microsoft Offensive Research & Security Engineering (MORSE) team.

This internal discovery demonstrates Microsoft’s proactive approach to identifying security flaws in its products before they can be exploited by malicious actors.

Currently, there is no evidence that this vulnerability has been publicly disclosed outside of Microsoft’s official channels, nor has it been exploited in real-world attacks.

The exploit code maturity is classified as “unproven,” meaning no working exploit code has been made publicly available.

Microsoft has indicated that an official fix is available, though specific details about the remediation process and affected Windows versions have not been fully detailed in the initial disclosure.

The company’s acknowledgment of the MORSE team’s work highlights the importance of internal security research in maintaining the integrity of widely used encryption systems.

Organizations and individual users who rely on BitLocker for data protection should prioritize applying any available security updates as soon as possible.

While the vulnerability requires physical access to exploit, the potential for unauthorized access to encrypted data makes this a serious concern for users who may be targets of sophisticated physical attacks, particularly in corporate or high-security environments.

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