New Flaw Bypasses Bitlocker Encryption

A new vulnerability allows attackers with device access to bypass Bitlocker encryption, exposing protected files. Microsoft has issued temporary fixes.

Microsoft has acknowledged a new security flaw, named YellowKey, that affects its Bitlocker disk encryption feature on Windows devices. The vulnerability, tracked as CVE-2026-45585, allows an attacker with access to a device to bypass Bitlocker's protection entirely. This enables them to read and write files on an encrypted drive, compromising data confidentiality and integrity. The risk is heightened by the public availability of a proof-of-concept exploit, which demonstrates how the attack can be carried out. The company is currently investigating the issue and considering a future security patch to resolve it permanently.

This vulnerability poses a serious threat to organizations that rely on Bitlocker to secure data on company laptops and workstations, especially for remote or traveling employees. Bypassing the encryption renders one of the most common data protection measures ineffective against attackers who gain physical or privileged access to a machine. For businesses, this could lead to data breaches, non-compliance with data protection regulations, and loss of sensitive intellectual property. The immediate availability of an exploit means that IT and security teams cannot afford to wait for a patch.

In response, Microsoft has released an advisory with temporary mitigation strategies. The company is urging administrators to implement these steps immediately to reduce the risk of an attack while a permanent solution is being developed. A primary recommendation is to enforce strict access controls to prevent unauthorized users from interacting with devices. Organizations should review Microsoft's official guidance and apply the recommended configurations to all affected Windows systems to safeguard their encrypted data.

The vulnerability undermines a core Windows security feature used by millions of businesses to protect sensitive data, and a public exploit increases the immediate risk of data breaches.

Companies using Bitlocker for data protection are at risk of data theft and compliance violations if devices are compromised. Immediate mitigation is required to protect sensitive corporate and customer information.