Ravie LakshmananAug 12, 2026Zero-Day / Vulnerability
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 as a race condition that, if successfully exploited, could grant an attacker the ability to spawn a shell with SYSTEM-level privileges, enabling them to run arbitrary code or perform unauthorized actions.
Although it was first disclosed by the researcher in June 2026, a patch for the vulnerability was not released by Microsoft until almost a month later. The tech giant described it as a privilege escalation issue in the Microsoft Malware Protection Engine ("mpengine.dll").
