DEV Community

Cover image for Your Next.js 16 MCP server is dangerously exposed
BeyondIT
BeyondIT

Posted on

Your Next.js 16 MCP server is dangerously exposed

Everyone is rushing to build Model Context Protocol (MCP) servers in Next.js 16. Giving AI coding agents like Cline or Claude direct read/write access to your local filesystem feels like a superpower.

Until it gets hijacked.

There is a massive security blind spot in how these agents parse context, and it's called Clinejection.

Read the full patch guide: Next.js 16 MCP Security: Fixing the Clinejection Vulnerability →

If you aren't aggressively sanitizing the data your MCP server feeds back to the LLM, a poisoned database entry or a rogue log file can overwrite the agent's system instructions. Suddenly, your helpful AI assistant is silently exposing your .env variables or executing unauthorized terminal commands on your behalf.

I just published a complete technical breakdown on how to patch the Clinejection vulnerability before it compromises your repository.

Inside the new guide, I cover the exact code you need to push:

  • The Anatomy of a Clinejection: How poisoned data forces the AI to break out of its operational sandbox.
  • Strict Context Sanitization: The exact Next.js 16 middleware required to strip malicious prompt-injections from your MCP payloads.
  • Resource Sandboxing: How to configure hard limits so your AI agents physically cannot touch sensitive directories.

Stop trusting raw context windows. Lock down your infrastructure.

Read the full patch guide: Next.js 16 MCP Security: Fixing the Clinejection Vulnerability →

Top comments (0)