Microsoft patches Windows Defender RoguePlanet vulnerability

Microsoft has released an emergency security update to patch a high-severity vulnerability in its Windows Defender antivirus software, a flaw that could allow attackers to take complete control of affected systems. The company issued the out-of-band patch on Wednesday, July 8, 2026, addressing the issue tracked as CVE-2026-50656, known as "RoguePlanet."

The vulnerability is an elevation-of-privilege flaw in the Microsoft Malware Protection Engine, the core component that powers Defender's scanning functions. If successfully exploited, an attacker with access to a standard user account on a Windows computer could escalate their privileges to "NT AUTHORITY\SYSTEM," the highest level of access, granting them full control over the device. Microsoft assigned the flaw a CVSS severity score of 7.8, noting the attack complexity is low and exploitation is "more likely."

The fix is included in Microsoft Malware Protection Engine version 1.1.26060.3008. Microsoft's default configuration automatically updates both malware definitions and the engine for most home users. Systems where Microsoft Defender is turned off and another antivirus product is active are not vulnerable, as the Defender...