Security researcher Nightmare Eclipse has published details of a new vulnerability in the latest versions of Windows, despite facing a legal threat from Microsoft weeks earlier. The bug, named ShieldBreak, could allow hackers to gain system-wide access to a user's device and data.
ShieldBreak reportedly takes advantage of a flaw in Windows Defender, the anti-malware and security engine built into Windows. A successful attack could allow a hacker to escalate their permissions from a low-level user to full access to the device and its data.
The researcher published a proof-of-concept exploit as a Windows app, which requires the user to run the app to exploit the bug. Security researcher Will Dormann verified that the bug works and that Windows Defender must be enabled for the exploit to function. The bug is said to work on Windows 10, Windows 11 (including version 25H2), and Windows Server 2025.
Microsoft has not yet released a patch for the ShieldBreak bug. A spokesperson for Microsoft did not immediately comment when contacted. This bug is considered a zero-day because Microsoft was given no time to patch it before its public disclosure.