Microsoft closes book on Nightmare Eclipse's RoguePlanet zero-day

Microsoft fixed the RoguePlanet zero-day, tracked as CVE-2026-50656, in the Microsoft Malware Protection Engine. Security researcher Nightmare Eclipse published exploit code in June, claiming the race condition bug granted SYSTEM privileges on fully patched Windows 10 and 11 systems. The fix closes all public zero-days disclosed by the researcher this year.