Supabase MCP can leak your entire SQL database

I have no association with Supabase, but in their defense, apart from adding a caution note, there's nothing else that Supabase needs to do, from my perspective.

As far as I am concerned, this is not a serious security hole if the human developer exercises common sense and uses widely recognized security precautions while developing their system.

This.

As a platform, where do you draw the line between offering a product vs not because a developer could do something stupid with it?

edit: keeping in mind the use cases they are pushing in their documentation are for local development

> this is not a serious security hole if the human developer exercises common sense and uses widely recognized security precautions

Just like SQL injection attacks aren't something to worry about, right?

Have we learned nothing from three decades of internet security experience? Really? Yes. It seems we've learned nothing. I weep for the future.

Database still support RAW queries. So, yeah developer are responsible for proper usage of the tools.

There are whole ecosystems of tools designed around the need to isolate queries, though. You don't just throw a Postgres prompt at your developers and tell them to be careful, because if you do little Bobby Tables pwns your stuff.

We know this is how this works. We lived through it. Why on earth do you think the results will be any different this time?

Database providers do just throw a postgres prompt at developers though, right? And that is what Supabase is – an infra provider.

Reflecting on this whole situation, I suspect MCP is fundamentally insecure, in which case Supabase should refuse to implement it.

MCP's goal is to make it easy for end user developers to impulsively wire agentically running LLM chats to multiple tools. That very capability fundamentally causes the problem.

Supabase's response (in the top comment in this post) of making it read-only or trying to wrap with an LLM to detect attacks... Neither of those help the fundamental problem at all. Some other tool probably has write capabilities, and the wrapping isn't reliable.

> MCP's goal is to make it easy for end user developers to impulsively wire agentically running LLM chats to multiple tools. That very capability fundamentally causes the problem.

That's exactly the problem here: the ability for end users to combine MCP tools means that those end users are now responsible for avoiding insecure tool combinations. That's a really hard thing for end users to do - they have to understand the lethal trifecta risk in order to make those decisions.

That's an argument, I guess, for absolving Supabase for explicit responsibility for the resulting hilarity. It's not an argument that MCP prompt hacking is "not a serious security hole", which is the point I responded to upthread.

It's only a security hole if you give access to users though, right? If you are the one using the Supabase MCP, how is it any different than any other root access to a DB?

Because of lethal trifecta attacks: https://simonwillison.net/2025/Jun/16/the-lethal-trifecta/

If you are the person using the LLM tool, a prompt injection attack in a database row that you are allowed to view could trick your LLM tool into taking actions that you don't want it to take, including leaking other data you are allowed to see via writing to other tables or using other MCP tools.