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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.
Microsoft fixes a major BitLocker bug… but leaves Windows 10 users hanging (for now)
Winsage
May 15, 2026

Microsoft fixes a major BitLocker bug… but leaves Windows 10 users hanging (for now)

Microsoft confirmed a BitLocker-related issue caused by the April 2026 Security Update (KB5083769) for Windows 11, which led some devices to boot into the BitLocker recovery screen. A fix has been released, but it is currently available only for Windows 11, version 25H2, with Windows 10 and Windows Server users awaiting a solution. Administrators are advised to remove the "Configure TPM platform validation profile for native UEFI firmware configurations" Group Policy setting before installing the April 2026 update. Additionally, a security researcher named Chaotic Eclipse has developed a zero-day exploit called YellowKey, which can bypass BitLocker security using a USB stick, affecting Windows Server 2022 and 2025 but not Windows 10.
Windows Zero-Days Expose BitLocker Bypasses And CTFMON Privilege Escalation
Winsage
May 14, 2026

Windows Zero-Days Expose BitLocker Bypasses And CTFMON Privilege Escalation

An anonymous cybersecurity researcher disclosed two new zero-day vulnerabilities affecting Microsoft systems: YellowKey and GreenPlasma. YellowKey is a BitLocker bypass that operates as a backdoor within the Windows Recovery Environment, impacting Windows 11 and Windows Server 2022/2025. Exploiting YellowKey involves copying specially crafted files to a USB drive, connecting it to a Windows computer, and rebooting into WinRE. The researcher expressed skepticism about Microsoft's response time to this vulnerability, noting that using TPM+PIN does not mitigate the risk. GreenPlasma is a privilege escalation vulnerability that allows an unprivileged user to obtain a shell with SYSTEM permissions through arbitrary section creation in Windows CTFMON. The proof-of-concept for this exploit is incomplete but indicates potential manipulation of trusted privileged services or drivers. Additionally, a related attack against BitLocker was detailed by French cybersecurity firm Intrinsec, which exploits a boot manager downgrade using CVE-2025-48804 to bypass encryption protections on fully patched Windows 11 systems. This method allows attackers to boot from a controlled WIM while the boot manager checks the legitimate one, executing with the decrypted BitLocker volume. Despite Microsoft releasing fixes for this defect in July 2025, a flaw in Secure Boot verification allows a vulnerable boot manager to bypass BitLocker safeguards. To mitigate these risks, enabling a BitLocker PIN at startup and migrating to a new boot manager certificate is recommended.
Windows BitLocker zero-day gives access to protected drives, PoC released
Winsage
May 13, 2026

Windows BitLocker zero-day gives access to protected drives, PoC released

A cybersecurity researcher known as Chaotic Eclipse has released proof-of-concept exploits for two unpatched vulnerabilities in Microsoft Windows: YellowKey, a BitLocker bypass, and GreenPlasma, a privilege-escalation flaw. The YellowKey vulnerability affects Windows 11 and Windows Server 2022/2025, allowing unauthorized access to BitLocker-protected volumes by exploiting the Windows Recovery Environment. The exploit can be executed using specially crafted 'FsTx' files on a USB drive or directly on the EFI partition. Independent researcher Kevin Beaumont has validated the exploit, which can bypass BitLocker protections even in a Trusted Platform Module (TPM) environment. The GreenPlasma vulnerability allows unprivileged users to create arbitrary memory-section objects, potentially leading to privilege escalation. Chaotic Eclipse has expressed dissatisfaction with Microsoft's handling of bug reports, prompting the public disclosure of these vulnerabilities. Microsoft has stated its commitment to investigating security issues and updating affected devices.
Microsoft Tests Point-in-Time Restore for Windows 11, a Full System Backup Beyond Classic System Restore
Winsage
May 8, 2026

Microsoft Tests Point-in-Time Restore for Windows 11, a Full System Backup Beyond Classic System Restore

Microsoft is testing a recovery feature for Windows 11 called Point-in-Time Restore, which offers a more extensive system snapshot than the traditional System Restore. It was first introduced in the Windows 11 Insider Experimental preview on April 24, 2026. The feature aims to minimize downtime and simplify troubleshooting and can be accessed through the Windows Recovery Environment and the Windows Settings app. Point-in-Time Restore backs up a broader range of data compared to System Restore, including user files, applications, settings, passwords, secrets, certificates, and keys. It restores the entire PC to a previous state, losing any local changes made after the snapshot. The feature operates on an automated schedule, with snapshots retained for up to 72 hours, and users can create new snapshots at specified intervals. For optimal use, Point-in-Time Restore is enabled by default on PCs with at least 200GB of drive space, with a storage cap of 2% of total drive capacity. It remains optional for consumer versions of Windows. A specialized version for Windows 365 Enterprise cloud PCs is always active, retains restore points for up to a month, and uses scalable cloud storage. Remote management support for Point-in-Time Restore is under development and not yet available. Currently, it is limited to builds within the Windows 11 Insider Experimental channel, with broader availability details pending.
Defender yanks root certs as Windows updates blocks backups
Winsage
May 5, 2026

Defender yanks root certs as Windows updates blocks backups

Microsoft's Defender anti-malware tool update version 1.449.425.0 removed two DigiCert root digital certificates, leading to false positives that flagged them as severe malware (Trojan:Win32/Cerdigent.A!dha). This incident was later identified as a false positive, and updating to version 1.449.430.0 or later reinstates the certificates. The issue may be linked to a DigiCert employee encountering disguised malware. Additionally, Windows updates from April 14 caused third-party backup applications to malfunction due to the addition of vulnerable psmounterex.sys kernel driver versions to a blocklist. Users experienced difficulties with mounting backup image files, and Microsoft referenced a vulnerability rated 9.3 out of 10 in the driver. Other affected software includes Acronis Cyber Protect Cloud and UrBackup server. Microsoft has not explained the delay in adding the vulnerable driver to the blocklist, and other recent update-related issues have also been reported.
Windows 11 KB5083769 causing a death loop on 24H2 and 25H2 systems
Winsage
April 25, 2026

Windows 11 KB5083769 causing a death loop on 24H2 and 25H2 systems

Microsoft's April 2026 Patch Tuesday update, KB5083769, has caused significant boot issues for Windows 11 users on versions 24H2 and 25H2. Users reported problems such as distorted visuals and the Blue Screen of Death after restarting post-update. The issue affects various hardware configurations, including HP and Dell systems. Additionally, the update may trigger BitLocker recovery on some systems, complicating recovery for users without their recovery key. Users have also experienced an increase in the number of restarts required during installation. Microsoft has not yet provided an emergency fix. Affected users are advised to use the Windows Recovery Environment for troubleshooting, including System Restore and Startup Repair. To check if KB5083769 is installed, users can go to Settings → Windows Update → Update history, and if present, it is recommended to uninstall it and pause updates.
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