A security researcher has published details of a new vulnerability in the latest versions of Windows that allows hackers to gain system-wide access to the user’s device and data, despite facing a legal threat from Microsoft weeks earlier over the release of previously unknown software flaws.
The new bug, dubbed ShieldBreak, is the latest disclosure by security researcher Nightmare Eclipse, who in recent months has published details of several bugs affecting Microsoft’s products, including Windows.
According to Nightmare Eclipse’s post, ShieldBreak takes advantage of a flaw in Windows Defender, the anti-malware and security engine built into Windows. A successful attack allows the hacker to escalate their permissions from a low-level user to full access to the device and its data.
Nightmare Eclipse published the proof-of-concept exploit as a Windows app, requiring the user to run the app to exploit the bug. The bug works on Windows 10, Windows 11 (including the latest 25H2 version), and Windows Server 2025, the researcher said.
Security researcher Will Dormann verified that the bug works and that Windows Defender must be enabled for the exploit to work.
