https://www.docker.com/blog/hardened-images-free-now-what/

Docker Hardened Images are now free, covering Alpine, Debian, and over 1,000 images including databases, runtimes, and message buses. For security teams, this changes the economics of container vulnerability management.

DHI includes security fixes from Docker’s security team, which simplifies security response. Platform teams can pull the patched base image and redeploy quickly. But free hardened images raise a question: how should this change your security practice? Here’s how our thinking is evolving at Docker.

DHI gives you a security “waterline.” Below the waterline, Docker owns vulnerability management. Above it, you do. When a scanner flags something in a DHI layer, it’s not actionable by your team. Everything above the DHI boundary remains yours.

The scope depends on which DHI images you use. A hardened Python image covers the OS and runtime, shrinking your surface to application code and direct dependencies. A hardened base image with your own runtime on top sets the boundary lower. The goal is to push your waterline as high as possible.

Vulnerabilities don’t disappear. Below the waterline, you need to pull patched DHI images promptly. Above it, you still own application code, dependencies, and anything you’ve layered on top.