Can ‘RoguePlanet’ still exploit Microsoft Defender despite the latest patches?

On June 10, 2026, a new zero-day vulnerability in Microsoft Defender, named ‘RoguePlanet,’ was revealed, capable of being exploited despite the latest Windows Update patches. This vulnerability was introduced by a security researcher known as Nightmare Eclipse, allowing remote code execution when a user accesses a file hosted on a remote SMB server. The flaw arises from a race condition, making its success variable across different machines. Cybersecurity firm ThreatLocker confirmed the vulnerability in their tests, noting its persistence beyond the recent updates. Nightmare Eclipse, who has a history of disclosing vulnerabilities like BlueHammer and RedSun, has expressed frustration with Microsoft’s bug bounty program, citing poor communication and account issues.