According to Microsoft itself, this update included security enhancements for key features in Windows 10, but also for peripherals such as mice, keyboards and pens.
Essentially, the KB4574727 is an important security update and it is obviously recommended that you install it immediately because it fixes vulnerabilities in the Microsoft operating system.
However, some users have found that installing the update on their devices due to its software Bitdefender. The protection mechanism mistakenly recognized her KB4574727 as a potential threat and while the download of the update could be completed via Windows Update, the protection application blocked the installation.
The file \Device\HarddiskVolume4\WINDOWS\SoftwareDistribution\Download\021b4073b65a625a58c006858ea0a97d\Windows10.0-KB4574727-x64.cab is infected with Trojan.Ciusky.Gen.13. The threat has been successfully blocked, your device is safe.
The easiest way to fix this problem is to add an exception to this Windows update so you can avoid isolating the files from its protection machine. Bitdefender.
Other users have tried to download the update from the Microsoft Update Catalog and attempt a manual installation with the same results.