NightmareEclipse Unleashes Windows Defender Zero-Day Ahead of Patch Tuesday
Security researcher NightmareEclipse has published ShieldBreak, a new Windows Defender zero-day that allegedly lets attackers gain full control of a Windows device and may bypass the RoguePlanet patch (CVE-2026-50656). Microsoft is investigating but has not confirmed the claims; external researchers say the POC is legitimate. Tests reportedly work on Windows 11 25H2, Windows Server 2025, and even Windows 10. The disclosure comes ahead of Patch Tuesday, continuing the feud between Microsoft and the researcher over Windows security.