Comment by chatmasta

Compartmentalization might make chaining the exploit more difficult, but it's certainly not unheard of. There have been exploit chains in the past that manage to jump from the baseband to the main CPU, for example.

One of my favorite exploits [0] was from Project Zero where the chain began with a vulnerability in the Apple wireless stack (Broadcom? maybe, but that might be a different exploit I'm thinking of), and ended in arbitrary kernel RCE. In other words, it was "a wormable radio-proximity exploit which allows me to gain complete control over any iPhone in my vicinity."

More relevantly to your question, here's a writeup about exploiting a GPU. [1]

[0] https://googleprojectzero.blogspot.com/2020/12/an-ios-zero-c...

[1] https://googleprojectzero.blogspot.com/2020/09/attacking-qua...