By Rachit Agarwal
Publication Date: 2026-08-16 10:53:00
Microsoft’s legal threats clearly didn’t scare off security researcher Nightmare Eclipse. Just weeks after the company warned it might pursue researchers who release undisclosed bugs outside its official channels, Nightmare Eclipse published a fresh Windows vulnerability, and it’s a nasty one.
What exactly does ShieldBreak do?
The new bug, called ShieldBreak, targets Windows Defender, the built-in anti-malware engine that ships with every copy of Windows. When exploited successfully, it lets an attacker jump from a low-level user account to full system access, essentially handing over the keys to your entire device.
Nightmare Eclipse released the proof of concept as a downloadable Windows app, meaning someone would need to actually run it for the exploit to work. According to the researcher, ShieldBreak affects Windows 10, Windows 11, and Windows Server 2025. Security researcher Will Dormann confirmed the bug works, though he noted Windows Defender needs to be turned on for it to…
