Tracking issue: all GitHub action scripts that use package caches should support read-only mode for the caches. #705

TLDR: Some base actions setup scripts do not support modes where all package caching is read-only.

We should add flags for caches to be used in read only mode

Context - cache poisoning attacks

Repositories using GitHub Actions that use agentic processing (coding agents) have been subject to cache poisoning attacks, e.g. https://rohittamma.substack.com/p/how-an-ai-prompt-injection-silently.

Security architectures that host agentic processing (i.e. coding agents) naturally want to make use of setup-node, and other basic setup actions. This is an acceptable design decision for those architectures.

It is a natural response of these archtictures to want all "agentic jobs" to run entirely in read-only mode apart from uploaded artifacts. Because of this, it's reasonable for these actions to want to use "actions/setup-node" and others entirely in read-only mode. So, with package cache reads still active, but cache updates turned off.

Recommendation

This is a tracking issue for this problem.

On a quick review, some base actions scripts do not support options for read-only package caches.

We will do further review and edit this issue description with our findings.