A recently identified security vulnerability, designated CVE-2025-48818, has raised concerns regarding the integrity of Windows BitLocker encryption. This flaw allows attackers to exploit a time-of-check time-of-use (TOCTOU) race condition, effectively bypassing the encryption feature. With a CVSS score of 6.8, the vulnerability is classified as having an Important severity rating and impacts multiple versions of Windows.
BitLocker’s TOCTOU Flaw (CVE-2025-48818)
This vulnerability specifically targets the BitLocker Device Encryption feature, which is designed to safeguard data at rest. The nature of the attack requires physical access to the target system, making it a direct threat rather than a remote exploitation risk. The attack complexity is low, and no user interaction is necessary, which heightens the potential for unauthorized access.
The CVSS 3.1 vector string indicates a significant impact on confidentiality, integrity, and availability, highlighting the critical nature of this flaw. Discovered by security researchers Alon Leviev and Netanel Ben Simon from Microsoft’s Offensive Research & Security Engineering (MORSE) team, this vulnerability underscores the value of proactive internal security research.
Exploiting this vulnerability allows attackers to circumvent BitLocker Device Encryption on system storage devices, undermining the protective measures that full-disk encryption is meant to provide. An attacker with physical access can manipulate the authentication sequence during a crucial timing window, thereby gaining unauthorized access to sensitive encrypted data, which may include user credentials, corporate information, and system configurations.
The vulnerability affects a wide array of Windows platforms, including:
- Windows 10 (versions 1607, 21H2, 22H2)
- Windows 11 (versions 22H2, 23H2, 24H2)
- Windows Server editions (2016, 2022, 2025)
Risk Factors | Details |
Affected Products | – Windows 10 (all versions: 1607, 21H2, 22H2) – Windows 11 (versions 22H2, 23H2, 24H2) – Windows Server 2016, 2022, 2025 – All architectures: 32-bit, x64, ARM64 – Both standard and Server Core installations |
Impact | Security Feature Bypass |
Exploit Prerequisites | Direct access to target system required, No authentication needed, No User Interaction |
CVSS 3.1 Score | 6.8 (Medium) |
Mitigation Strategies
In response to this vulnerability, Microsoft has released a series of security updates designed to address CVE-2025-48818 across all affected Windows versions. Key patches include build numbers for Windows 10 22H2 (10.0.19045.6093), Windows 11 23H2 (10.0.22631.5624), and Windows Server 2025 (10.0.26100.4652). Organizations are urged to apply these updates promptly through their standard patch management processes.
System administrators should prioritize the installation of security updates KB5062552, KB5062553, KB5062554, and KB5062560, depending on their specific Windows version. Additionally, it is advisable for organizations to enhance physical security measures to restrict unauthorized access to BitLocker-protected systems, given that the vulnerability necessitates physical proximity to the target device. Regular security audits and monitoring for unauthorized access attempts can further bolster defenses while patches are deployed throughout enterprise environments.