Microsoft has recently disclosed a critical security vulnerability in Windows BitLocker, identified as CVE-2025-48818. This flaw, officially released on July 8, 2025, impacts the disk encryption system relied upon by millions of users for data protection. The vulnerability is categorized as a “time-of-check time-of-use (TOCTOU) race condition,” which allows malicious actors to circumvent BitLocker’s security mechanisms by exploiting a brief window between when a security condition is checked and when a resource is actually utilized.
The vulnerability carries an “Important” severity rating from Microsoft, with a CVSS score of 6.8 out of 10, signifying a substantial risk.
What makes this flaw particularly concerning is its low attack complexity: it requires no user interaction or special privileges, making it accessible to attackers who can gain physical access to a target device. While the need for physical access somewhat limits its scope compared to remote exploits, the straightforward nature of the exploitation once physical access is achieved presents a significant threat.
Successful exploitation of this race condition could lead to complete compromise of protected information, as indicated by the high impact ratings across confidentiality, integrity, and availability. This means attackers could potentially gain unauthorized access to encrypted data by manipulating the timing of security checks. Organizations that use BitLocker for disk encryption are urged to address this vulnerability with urgency, especially in environments where robust physical security cannot be guaranteed.
Microsoft has confirmed that an official fix for CVE-2025-48818 is now available.
Though the exploit code maturity is currently “unproven,” suggesting that widely available exploit code has not yet emerged. Nevertheless, security experts strongly advise immediate patching of affected systems. This proactive measure is crucial to prevent potential exploitation, as attack techniques are continuously evolving and becoming more sophisticated.
FAQ
A successful attacker could bypass the BitLocker Device Encryption feature on the system storage device. An attacker with physical access to the target could exploit this vulnerability to gain access to encrypted data.
Acknowledgements
- Alon Leviev with Microsoft Offensive Research & Security Engineering (MORSE)
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Netanel Ben Simon with Microsoft Offensive Research & Security Engineering (MORSE)
Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure.
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