Microsoft has resolved the "RoguePlanet" zero-day vulnerability, designated as CVE-2026-50656, in its Microsoft Defender product. This fix was implemented through an update to the Microsoft Malware Protection Engine, rather than as part of the company's regular Patch Tuesday updates. The vulnerability was initially disclosed by security researcher Nightmare Eclipse in June, sparking a public debate over Microsoft's handling of vulnerability reports. To receive the patch, customers must ensure they are running the latest version of the Microsoft Malware Protection Engine. The resolution of this vulnerability is significant, as it was actively being discussed and its exploitation status would determine the urgency of the patch1. This fix is crucial for practitioners, as it mitigates a potential zero-day exploit, emphasizing the importance of keeping security software up to date to prevent attacks.