Microsoft has officially confirmed the existence of a zero day vulnerability in Microsoft Defender known as RoguePlanet and announced that a security update is currently being developed to address the issue. The vulnerability has been assigned CVE 2026 50656 and carries a CVSS severity score of 7.8. According to Microsoft, the flaw affects the Microsoft Malware Protection Engine and can be exploited to achieve elevation of privilege on affected systems. The company’s acknowledgement follows public disclosure of the vulnerability by security researcher Chaotic Eclipse, also known as Nightmare Eclipse, who released proof of concept details demonstrating how the flaw could be used to obtain SYSTEM level access on vulnerable machines. Microsoft stated that it is aware of the issue and is focused on delivering a high quality security update to mitigate the risk posed by the vulnerability.
The RoguePlanet disclosure emerged nearly a week after the researcher publicly detailed the exploit and described it as a race condition vulnerability capable of granting attackers highly privileged access. According to the researcher, successful exploitation can result in a shell running with SYSTEM level permissions, providing extensive control over the targeted system. The researcher noted that the exploit’s reliability varies depending on the environment, describing it as a hit or miss scenario. In some cases, the proof of concept achieved a 100 percent success rate, while in other environments it struggled to execute consistently. Despite these inconsistencies, the disclosure generated significant attention within the cybersecurity community due to the potential impact associated with SYSTEM level privilege escalation. Such access can allow attackers to bypass standard user restrictions, manipulate security settings, install malicious software, and maintain persistence within compromised systems.
Additional information shared by Chaotic Eclipse has raised further concerns regarding the vulnerability’s effectiveness under different Microsoft Defender configurations. In a follow up update published earlier this week, the researcher stated that the proof of concept appears to function regardless of whether real time protection is enabled or disabled. The researcher also indicated that the exploit may potentially work when Microsoft Defender is operating in passive mode, although that scenario had not been fully tested at the time of disclosure. These observations suggest that common defensive configurations may not be sufficient to prevent exploitation until an official security update becomes available. Security professionals continue to monitor the situation closely as organizations assess potential exposure and await Microsoft’s remediation efforts.
Microsoft had previously told The Hacker News that it was aware of the reported vulnerability and was actively investigating the validity and applicability of the claims. The company’s latest statement confirms that the issue has now been formally recognized and assigned a CVE identifier. RoguePlanet represents the fourth Microsoft Defender related vulnerability publicly disclosed by Chaotic Eclipse. Previous discoveries attributed to the researcher include BlueHammer tracked as CVE 2026 33825, UnDefend tracked as CVE 2026 45498, and RedSun tracked as CVE 2026 41091. Microsoft has already issued patches for those vulnerabilities following their disclosure. The emergence of RoguePlanet highlights the continued scrutiny of endpoint security technologies and the importance of rapid vulnerability response processes. As organizations increasingly rely on built in security solutions such as Microsoft Defender to protect enterprise environments, vulnerabilities affecting core security components remain a significant area of concern for defenders and software vendors alike while remediation efforts are underway.
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