Motion Site Builder is a library of prompts, Markdown references, and a small suite of zero-dependency Python tools (a motion linter, a corpus indexer, and an MCP server that speaks JSON-RPC over stdio). It ships no runtime service, handles no user data, and requires no credentials. The attack surface is correspondingly small, but we take it seriously.

Realistic concerns we care about:

• The MCP server or linter mishandling untrusted input (a malformed file path, a hostile code string passed to motion_validate, a crafted JSON-RPC frame) in a way that reads outside the repo, hangs, or executes unintended code.
• The build_index.py corpus scanner following a path it shouldn't.
• A supply-chain issue in the landing page under site/ (its npm dependencies), even though it is a static demo.

Out of scope: the aesthetic quality of generated sites, licensed media source pages recorded for provenance (direct third-party asset hotlinks are not shipped; downloaded files remain the user's responsibility), and issues in AI builders (Bolt, Lovable, v0, Cursor) that consume the prompts.

Please do not open a public issue for a security problem.

Use GitHub's private advisory flow: Report a vulnerability (Security → Advisories → Report a vulnerability on the repository).

Include, where you can: affected file or tool, a minimal reproduction, the observed vs. expected behavior, and any suggested fix. A proof-of-concept that stays within your own environment is welcome.

• Acknowledgement within 5 business days.
• An initial assessment (severity, scope, whether it's in scope) shortly after.
• A fix or mitigation for confirmed, in-scope issues, and credit in the release notes if you'd like it.

Because this is a small open-source project maintained on a best-effort basis, timelines are targets, not guarantees. Thank you for helping keep it safe.

The latest release on main is the only supported version. Fixes land there and ship in the next tagged release.