Put the summary of the bug you're having here
EnderPearling, Horses..
What I expected to happen was...:
I have a faction server and people use ender pearls & horses to glitch into bases, i have disabled enderpearling,

What actually happened was...:
People go under the base with enderpearls they trow it up and half of theyr body gets stuck on the material, then they just trow another one and they get in, it works with the nether bedrock on top, works with anything basically you can bypass any block you want with ender pearls,
horses:
people spawn in a horse below a base and then they just walk below it when they get stuck they just leave the horse and spawn in the base

Steps to Reproduce:
1. I did that above ^^^