Because it uses exploits (often known as "dirty cow" or "futex" vulnerabilities), your device remains technically vulnerable to those same exploits after rooting. A malicious app could use the same hole to gain unauthorized access. Install SuperSU over Kingroot using a script like SuperSU-me to replace the KingUser manager.
This specific build stands as a monument in the history of Android customization. It represents the peak efficiency of the "one-click root" method. For users holding onto legacy devices or those looking to understand the evolution of Android security, revisiting this specific APK is a journey into the golden age of mobile modification.
This version will almost certainly NOT work on Android 7.0 Nougat or newer. For Android 8+, look for Kingroot 6.x or Magisk.