Microsoft released a patch on July 9, 2026, to address a zero-day vulnerability in its Defender security engine, identified as RoguePlanet (CVE-2026-50656). The vulnerability, disclosed by a researcher known as NightmareEclipse in June, allows remote attackers to gain administrative control of Windows 10 and Windows 11 machines, even with real-time protection disabled. The patch updates the Microsoft Malware Protection Engine, which is used by the Defender antivirus application, and will be automatically downloaded and installed on users' devices. The update also includes additional security improvements.
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Microsoft Releases Patch for Zero-Day Vulnerability in Windows Defender
On July 9, 2026, Microsoft issued a patch for a zero-day vulnerability in its Defender security engine, known as RoguePlanet. This vulnerability could allow remote attackers to gain administrative control of Windows machines. The patch will be automatically installed on users' devices.
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Patch for Windows Defender 0-day could allow attackers to fill hard disk
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Microsoft Releases Patch for Zero-Day Vulnerability in Windows Defender