Microsoft Defender Zero-Day Exploit Bypasses Patch, Enables SYSTEM Access

A proof-of-concept (PoC) for the ShieldBreak zero-day vulnerability demonstrates a patch bypass in Microsoft Defender, enabling SYSTEM-level access through a flaw in CVE-2026-50656 (RoguePlanet). Microsoft is investigating claims that its patch for the vulnerability failed to fully address the issue, while other critical flaws were also remediated.

The security researcher going by the name Chaotic Eclipse (aka INFINITE NIGHTMARE, MSNightmare, and Nightmare-Eclipse) has released a proof-of-concept (PoC) for a new Microsoft zero-day called ShieldBreak.

The vulnerability, rooted in Microsoft Defender for Windows, demonstrates a patch bypass for CVE-2026-50656 (CVSS score: 7.8), otherwise known as RoguePlanet.

RoguePlanet has been described

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