Players have been reporting hackers all over the place in Fallout 76 but Bethesda have dismissed their claims. They might just have some merit though as hacking is not really hard to pull of for the moment, but is expected to be patched.
Fallout 76 fans have vented their frustrations on Reddit recently, by posing threads about mods that are actually cheats. Several media outlets picked up on this and reported the issue, but Bethesda first claimed these concerns are not valid but then also stated they are "aware and investigating the issue".
A disgruntled Redditor gave a few examples of how one can easily cheat in Fallout 76 by simply editing the .esm file, which is an archive of essential files for Fallout 76. Editing .esm files was done in previous Bethesda games when modding, but one actually makes a plugin file to load after .esm in order to change certain parameters or add new content in and that is exactly the same way Bethesda's DLC was handled.
In this particular case, the Reddit poster, going by the name teetharejustdone, Bethesda aren't forcing validation of file integrity so players can just edit the .esm as much as they want. For example, they can resize objects in the game or make colours brighter for better visibility, walk through walls, gain info on other players such as health and location, or even make their character have infinite health.
The last but not the least of the exploits is everyone's favourite - DDoSing. Bethesda's official was initially that "Many of the claims in the thread are either inaccurate or based on incorrect assumptions. The community has however called to attention several issues that our teams are already actively tracking and planning to roll out fixes for". This is a rather odd pair of sentences, since the first demants the claims while the end of the next sentence confirms them.
Bethesda continued on to say that "Cheating or hacking will not be tolerated" even though modding is something they are going to support down the line. This probably means when the private servers come along, which is not going to happen until November 2019.