Open-source bastyn statically scans MCP and coding-agent configs for risks
claudio-rootedlogic · reddit · 2026-11-14
The author open-sourced bastyn (Apache-2.0), a deterministic static scanner that uses no LLM to check MCP configs, coding-agent instructions and skills, source code, Docker/Compose files, and dependencies.
- Flags: unpinned npx MCP servers, autoApprove wildcards and plaintext credentials, Docker socket mounts, plaintext HTTP, OSV-known dependency vulnerabilities.
- Inspects MCP tool descriptions (Python docstrings or remote tool lists via --inspect-remote) for hidden instruction-override text and skill text that fetches and runs code.
- Low-false-positive design: anything not provable from the code is a non-failing "observation"; findings crosswalk to EU AI Act and NIST areas.
- Install via brew/cargo, GitHub Action support, SARIF output, --fail-on gating, and npx skills add for coding agents.
- Limits: alpha, not runtime protection, Python-only single-file dataflow tracking; default-on anonymous telemetry can be disabled with --offline.
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