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CVE-2026-45585: YellowKey BitLocker Bypass
Winsage
May 23, 2026

CVE-2026-45585: YellowKey BitLocker Bypass

BitLocker, a security feature for data protection, has a vulnerability identified as CVE-2026-45585, also known as YellowKey, which allows unauthorized access to encrypted data on Windows 11 versions 24H2, 25H2, 26H1, and Windows Server 2025. This flaw does not compromise BitLocker’s encryption but affects the recovery environment supporting it. The vulnerability can be exploited locally through the Windows Recovery Environment (WinRE) by an attacker with physical access, who can trigger an unrestricted shell and access the BitLocker-protected volume. Microsoft has provided two mitigation strategies: modifying the WinRE image to remove the autofstx.exe entry and transitioning from TPM-only protection to a TPM+PIN requirement at startup. The exploit poses challenges for detection, as it occurs pre-boot and currently lacks vendor-published indicators of compromise. Organizations using BitLocker for unattended devices are particularly at risk, as the vulnerability can lead to loss of confidentiality if an attacker gains access before the legitimate user.
Microsoft says public sharing of Windows 11 vulnerability violates 'best practices'
Winsage
May 22, 2026

Microsoft says public sharing of Windows 11 vulnerability violates ‘best practices’

A security researcher known as Nightmare-Eclipse revealed a vulnerability in Windows 11, named YellowKey, which allows attackers to access BitLocker-encrypted drives through the Windows Recovery Environment. Microsoft acknowledged the vulnerability, assigned it the identifier CVE-2026-45585, and criticized the public sharing of its proof of concept. Currently, there is no patch available for the BitLocker bypass, but physical access to the device provides some protection. The vulnerability does not exist in Windows 10 due to differences in the Windows Recovery Environment. The attack requires a stolen Windows 11 laptop and a USB stick, and the vulnerable filesystems include NTFS, FAT32, and exFAT. Nightmare-Eclipse speculated that the bypass may function as a backdoor, while Microsoft referred to it as a "security feature bypass vulnerability."
Microsoft shares mitigation for YellowKey Windows zero-day
Winsage
May 20, 2026

Microsoft shares mitigation for YellowKey Windows zero-day

Microsoft has addressed the YellowKey vulnerability, a zero-day flaw in Windows BitLocker identified as CVE-2026-45585. This vulnerability allows unauthorized access to BitLocker-protected drives through a specific exploitation process involving 'FsTx' files. The flaw was disclosed by an anonymous researcher known as 'Nightmare Eclipse.' Microsoft has released mitigation strategies, including removing the autofstx.exe entry from the Session Manager's BootExecute REGMULTISZ value and reestablishing BitLocker trust for WinRE. Additionally, users are advised to change BitLocker settings from "TPM-only" to "TPM+PIN" mode, requiring a pre-boot PIN for drive decryption, and to enable "Require additional authentication at startup" for unencrypted devices.
How To Mitigate The Microsoft Windows BitLocker ‘Angry Hacker’ 0-Day
Winsage
May 20, 2026

How To Mitigate The Microsoft Windows BitLocker ‘Angry Hacker’ 0-Day

Microsoft is addressing a zero-day exploit known as YellowKey, identified as CVE-2026-45585, which allows attackers to bypass BitLocker security using a specially crafted USB device. Following the release of exploit code by a hacker named Chaotic Eclipse, Microsoft has issued urgent mitigation advice. Cybersecurity expert Neena Sharma recommends treating this as an active threat and suggests implementing compensating controls, such as restricting USB boot access, until a patch is available. Microsoft has provided guidance for users to protect their systems, including the recommendation to add a PIN to BitLocker protection to reduce the risk of exploitation. Detailed instructions for adding a PIN are included in the advisory. YellowKey has not yet been exploited in the wild but requires physical access to the device.
Microsoft confirms Windows 11 security update install issues
Winsage
May 18, 2026

Microsoft confirms Windows 11 security update install issues

Microsoft has acknowledged a significant issue with the May 2026 Windows 11 security update, KB5089549, where users are encountering difficulties in installation, specifically the 0x800f0922 error code. This issue is primarily due to insufficient free space on the EFI System Partition (ESP), especially for devices with 10 MB or less available. The installation may fail during the reboot phase at around 35–36% completion, with users receiving notifications like "Something didn't go as planned. Undoing changes." Log entries may indicate insufficient ESP free space, such as "SpaceCheck: Insufficient free space" and "ServicingBootFiles failed. Error = 0x70." Microsoft recommends affected users utilize the Known Issue Rollback feature to reverse problematic updates and advises IT departments to install and configure the relevant Group Policy to address the issue.
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