A zero-day exploit in Microsoft Defender has been uncovered by researcher Chaotic Eclipse, granting SYSTEM privileges on fully patched Windows systems. The RoguePlanet exploit leverages a race condition to provide attackers with the highest level of permissions, allowing them to execute arbitrary code. This vulnerability has been successfully tested on up-to-date Windows 10 and Windows 11 systems, highlighting the severity of the issue. The fact that the exploit works on fully patched systems1 underscores the need for immediate action to assess potential exposure. The release of this proof-of-concept exploit means that the window for patching is rapidly shrinking, making it crucial for practitioners to evaluate their systems' vulnerability to this zero-day threat. The ability to gain SYSTEM-level privileges on fully updated systems puts entire networks at risk, so it is essential for security teams to take prompt action to mitigate this vulnerability.