A recent (but thankfully optional) Windows 10 cumulative update had resulted in Cortana taking over an entire CPU core, resulting in worse performance. Microsoft has addressed that flaw with Patch Tuesday’s KB4515384, which fixes SearchUI.exe.
The update also provides protections against Microarchitectural Data Sampling (a new subclass of speculative execution side-channel vulnerabilities) for 32-bit (x86) versions of Windows, as well as security enhancements for Internet Explorer, Microsoft Edge, networking technologies, and input devices.
It’s also worth mentioning that Microsoft has addressed two zero-day security vulnerabilities. These two vulnerabilities are elevation of privilege (EoP) flaws. The first one impacts the Windows Common Log File System (CLFS) driver while the second impacts the ws2ifsl.sys (Winsock) service.