Actions lockfiles prevent this. They won't allow you to lock an impostor commit, which is the right default.

(The previous way to provide general actions immutability, i.e. hash-pinning, had this issue and thus required additional checks.)

One could write an action that executes a shell script that does docker pull abc:latest.

As the consumer of an action that becomes really hard to find out unless I take the whole codebase apart.

Why not make the marketplace published tags immutable instead like others do?

That’s exactly what lockfiles are intended to avoid!

I almost forgot about that completely outrageous treatment of forks -- just bonkers.