Markdown sanitizers

This repository contains 2 related npm packages concerned with hardening markdown against data exfiltration attacks through LLM prompt-injection.

The 2 projects which address 2 different use cases:

1. You render the markdown to HTML yourself
2. You're giving the markdown to a third-party such as GitHub or GitLab where you don't control the rendering

You render the markdown to HTML yourself

This is the more common use-case. It's also the variant that is easier to secure, because you have full control over the process. harden-react-markdown is a wrapper for the popular react-markdown package giving it more secure defaults, and giving you the ability to allow-list URL prefixes in images and links.

2. You're giving the markdown to a third-party such as GitHub or GitLab where you don't control the rendering

We created markdown-to-markdown-sanitizer for this use-case. Generally speaking, this is less secure than sanitizing the final rendered output such as the generated HTML. Hence, this package should only be used when the markdown is rendered by a third-party such as GitHub or GitLab.

Security properties

The packages in this repository have subtle security properties. Use at your own risk (see LICENSE) and perform your own security testing for specific application.