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Show HN: Runtime Defense Against Prompt Injection in Supabase MCP
I wrote this after studying the Supabase MCP prompt injection issue. The blog shows how I built a working defense using an open-source AI agent runtime I’ve been building called Tansive ( https://github.com/tansive/tansive https://github.com/tansive/tansive )
Instead of just filtering malicious prompts, I implemented role-based policies with runtime input validation that can scale across combinations of different AI tools (GitHub, Stripe, Linear, etc.).
All the code referenced in the blog is in the examples/supabase_demo folder.
I welcome your feedback — especially from folks working with AI toolchains or security.
- anand-tan 1y agoFor reference, this was the thread that led me to work on this. https://news.ycombinator.com/item?id=44502318 https://news.ycombinator.com/item?id=44502318
- vijivishali 1y agoSince it's postgres behind the scenes, can't you just use pg roles?
- anand-tan 1y agoAbsolutely. If the tools were only from Supabase, then yes, you could use Postgres roles. However, most people use a combination of tools (GitHub, Stripe, Linear, etc.), and each has different permission models. I wanted to implement a solution that works generically across tools rather than requiring separate security configurations for each service. This doesn't preclude one from limiting the access scope at the database, though.