Microsoft patches RoguePlanet Defender zero-day vulnerability

Microsoft released a patch for a Microsoft Defender zero-day tracked as CVE-2026-50656, dubbed "RoguePlanet," which a researcher known as "Nightmare Eclipse" publicly disclosed along with a proof-of-concept. The flaw is a race condition enabling elevation to SYSTEM on fully patched Windows 10/11; Microsoft mitigated it by updating the Microsoft Malware Protection Engine (1.1.26060.3008). The disclosure prompted a dispute between the researcher and Microsoft, but the report does not document confirmed widespread exploitation.