Let's say I am "User". I subscribe through a "Third Party" to use "AI Agent" allowing an "LLM" to run.

I want to accomplish some legal non-nefarious task, and run the agent. The agentic loop causes a CFAA-violating behavior.

Who gets prosecuted?

1. User

2. The third party model host with whom I have the account

3. The developer of the harness /agent software

4. The developer of the LLM model

"Who gets prosecuted?" depends on the size of the perpetrator and victim (lone individual or employee of large corporation), egregiousness of the violation, and either financial appetite of the victim to bring a civil lawsuit or the desire of law enforcement to prosecute a criminal offense.

Who should get prosecuted is also up for debate, but generally makers of a tool don't get prosecuted when that tool has all sorts of legit uses. If you used a car to make your getaway from a bank robbery, the auto manufacturer who made it and the dealer who sold it to you should not be held culpable.

note the user because they did not have the intent

No one. Probably a fine tho and maybe accelerate reguations.

Intent is pretty important here so the user would have to prove that they didn't purposely disguise their prompt as non-nefarious which should be easy and then it stops at #2 and face the litmus test as in did you intentionally make a product for nefarious purposes which from your scenario is unlikely.

agentic loop going haywire and bringing down some government infrastructure then its a different story then everybody is on the hook including the user.