Very recently, a group of leakers, who leak software and operating systems, have leaked a Windows Core OS Build. It is an early build of Polaris, which was a cancelled SKU of Windows Core Operating system. The leaked build contains only the bare core operating system, which implies that it does not contain any app or composer. So, the leaked operating system does not have much interesting things to offer. The main objective of Windows Core OS is to create a universal modular Windows operating system.
The Windows Core operating system is not like a traditional operating system. The modular structure offers enhanced security, and can perform to even low end hardware, better battery. However, Polaris was cancelled at a time when Andromeda was also cancelled. Then, both these SKUs were succeeded by Windows 10X. It was codenamed SKU.
The leaked build is RS3 RTM but it does not have any confidential data that might be vulnerable. It does not have any GUI, any inbox application. The only purpose it will serve is that tech addicts may fidget with the OS for knowledge and interest. The leaked build is ARM32 architecture, which means it can only boot on older ARM32-based PCs like the Surface RT.