It could be a virus or malware
Wmpnetwk.Exe Process High CPU and Memory Usage FIX [Tutorial]
Windows Media Player (WMP) has a media sharing functionality that allows you to stream your PC's media library to other devices over a network. Wmpnetwk.exe is the process that handles the media sharing service in the background.
When you first enable media sharing in WMP, wmpnetwk.exe immediately begins indexing your media library. You may notice a spike in CPU usage during this operation, or when you stream media files to other devices.
That should go down once your files are successfully indexed. If wmpnetwk.exe continues to take up system resources when you are not sharing media files, proceed to the troubleshooting steps below. But first, check the safety and legitimacy of the wmpnetwk.exe file.
