Question about computer security/internet

[Nubitcoinerr]

So if I share someone elses mobile hotspot login for example my stepdad and family all use the same unlimited mobile xfinity hotspots plan where there are internet at millions of spots.

Could someone within the plan hack another person via the network? For example my cousin could he hack my device logged on to a hotspot or vice versa because we can see each other devices?

[Vod]

So if I share someone elses mobile hotspot login for example my stepdad and family all use the same unlimited mobile xfinity hotspots plan where there are internet at millions of spots.

Could someone within the plan hack another person via the network? For example my cousin could he hack my device logged on to a hotspot or vice versa because we can see each other devices?

The quick and simple answer is yes, someone could.  The potential is there, via undocumented bugs and security flaws.