Microsoft has issued a security update to fix a critical zero-day vulnerability in Defender, referred to as “RoguePlanet.” This flaw, identified as CVE-2026-50656, was brought to light by a security researcher known as “Nightmare Eclipse,” amid a dispute over Microsoft’s bug bounty and disclosure practices. The vulnerability impacts fully updated Windows 10 and 11 systems, enabling unauthorized command prompt access with SYSTEM privileges through a race condition in Microsoft Defender. Although the exploit’s success varies across devices, the researcher claims a perfect success rate on some. Microsoft has addressed this issue by releasing an update to the Microsoft Malware Protection Engine. This update, version 1.1.26060.3008, enhances the core scanning engine of its security solutions. Over recent months, Nightmare Eclipse has exposed several other Windows zero-day vulnerabilities, some affecting Microsoft Defender and others targeting BitLocker and Windows components. Microsoft has responded to these disclosures with legal warnings against activities it deems harmful to its customers, suggesting potential legal action against the researcher.
Has Microsoft patched the RoguePlanet Defender vulnerability?
