Microsoft Confirms RoguePlanet Defender Zero-Day, Says Patch is in Development

Ravie LakshmananJun 17, 2026Endpoint Security / Vulnerability * Microsoft has formally disclosed that it's working to release a patch to address a Defender zero-day codenamed RoguePlanet.

The vulnerability has now been assigned the CVE identifier CVE-2026-50656 (CVSS score: 7.8), with the tech giant describing it as a privilege escalation flaw.

"Microsoft is aware of an elevation of privilege in the Microsoft Malware Protection Engine in Microsoft Defender, publicly referred to as 'RoguePlanet,'" the company said. "We are working to provide a high-quality security update that addresses this vulnerability."

The development comes nearly a week after a security researcher named Chaotic Eclipse (aka Nightmare-Eclipse) released RoguePlanet, calling the exploit a case of a race condition that grants attackers a shell with SYSTEM-level privileges.

* "The exploit is a race condition, so it's a hit or miss," the researcher noted. "I have managed to get a 100% success rate on some machines while it struggled to work on others."

In an update shared Tuesday, the researcher added: "I forgot to add one thing, surprisingly, the PoC for RoguePlanet works regardless if real-time protection is on or not, which is hilarious. I think it even works in the case of passive mode, but not really sure, haven't tested that."

Microsoft told The Hacker News last week that it's aware of the reported vulnerability and that it's "actively investigating the validity and potential applicability of these claims."

RoguePlanet is the fourth Defender vulnerability disclosed by Chaotic Eclipse after BlueHammer (CVE-2026-33825), UnDefend (CVE-2026-45498), and RedSun (CVE-2026-41091), all of which have since been patched by Microsoft.

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