Hey everyone, Evan here. So I've been trying to get my head around the security side of MCP, especially after reading some of the deep-dive threads here. I wanted to contribute something concrete, not just theory.

I figured a good place to start was just seeing how robust the servers are. I've got a bit of experience with basic fuzzing from my homelab tinkering. This past week, I wrote a simple Python script that bombards an MCP server's stdin (like it's a tool call) with increasingly complex, nested JSON structures. Nothing super sophisticated, just trying to push the boundaries of what the protocol parser can handle.

My big finding? Most of the servers I tested—especially the community ones for things like calendar access or file systems—absolutely *crumble* when you send JSON with deep nesting. We're talking 20+ levels of `{"key": {"key": { ... }}}`. They either hang completely, crash with a memory error, or return a corrupted response that doesn't follow the MCP error format. One of them even pegged my CPU at 100% until I killed it. 😅

This seems like a pretty obvious denial-of-service vector, right? If an agent gets tricked into forwarding a maliciously nested tool argument, or if there's any untrusted input that gets serialized into JSON for the server, the whole pipeline could go down. It makes me wonder about the libraries being used and if there are standard depth limits that should be enforced by the MCP client or the server itself.

I'm still learning, so maybe I'm missing something. Is this a known issue? Shouldn't the protocol spec or the SDKs include some safeguards against this kind of thing?