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Microsoft has revealed a serious flaw in Windows BitLocker, known as CVE-2026-45585. The flaw was made public on May 19, 2026. No one has confirmed it is being used, but Microsoft says it is “Exploitation More Likely,” to be exploited, so quick action is needed.
The flaw is known as a Security Feature Bypass and has a high seriousness level of Important. Security audit services
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It is located in the Windows Recovery Environment (WinRE) and is linked to an important exploit chain called YellowKey, created by researcher Nightmare-Eclipse and shared on GitHub.
A successful attacker can take advantage of this problem to bypass BitLocker Device Encryption on the storage device, getting access to encrypted data without needing user passwords or decryption keys.
The flaw only affects Windows 11, Windows Server 2022, and Windows Server 2025.
No update is out yet; Microsoft has provided a guide with several steps to help while they work on a security fix.
Microsoft’s Mitigation Steps
Microsoft has provided a six-step mitigation procedure targeting the WinRE image directly:
To address the risk, the following mitigations have been outlined:
Mount the WinRE image on each device.
Mount the system registry hive of the mounted WinRE image.
Modify BootExecute by removing “autofstx.exe” value from Session Manager’s BootExecute REG_MULTI_SZ value.
Save and unload Registry hive.
Unmount and commit the updated WinRE image.
Reestablish BitLocker trust for WinRE.
Security teams running Windows 11 or Server 2022/2025 should focus on the WinRE fixing steps and apply TPM+PIN rules right away, before an official update comes out.
