The xhost program is used to add and delete host names or user names to the list allowed to make connections to the X server1. In the case of hosts, this provides a rudimentary form of privacy control and security. It is only sufficient for a workstation (single user) environment, although it does limit the worst abuses1. However, if xhost is used togrant access to everyone, even if they aren't on the list (i.e., access control is turned off), then any user on the network can connect to your X server and monitor your keystrokes, capture your screen, or run malicious programs2. This is why xhost is considered dangerous to use and should be avoided in favor of more secure methods, such as xauth or ssh23. References:
* xhost linux command man page - commandlinux.com
* Linux Xhost Command Help and Examples - Computer Hope
* xhost(1) - Arch manual pages