MCP Security Scanner

Why MCP Server Security Matters in 2026

A February 2026 security scan found over 8,000 MCP servers exposed on the public internet with no authentication. Any AI agent — or malicious actor — can connect to those servers, enumerate their tools, and call them without restriction.

Palo Alto Unit 42 published research in early 2026 identifying new attack vectors specific to MCP: tool poisoning (manipulating tool descriptions to hijack agent behavior) and sampling injection. Both require an attacker to first reach your server — authentication is your first line of defense.

This free scanner checks the most critical security properties of your MCP server and gives you a prioritized list of what to fix.

What This Scanner Checks

• HTTPS: Whether your server uses TLS. HTTP servers expose auth tokens, session data, and tool payloads in plaintext — any network observer can intercept them.
• Authentication Required: Whether the server rejects unauthenticated requests with a 401 or 403. This is the most important check — an open server is fully accessible to anyone.
• HTTP Strict Transport Security (HSTS): Prevents browsers from falling back to HTTP connections and protects against SSL stripping attacks.
• X-Content-Type-Options: Prevents MIME type sniffing, which can enable cross-site scripting in some browser configurations.
• X-Frame-Options: Blocks your server's responses from being embedded in iframes, preventing clickjacking attacks.
• Content-Security-Policy: Restricts which resources can be loaded, providing a strong second line of defense against XSS.
• CORS Policy: A wildcard Access-Control-Allow-Origin: * means any website can make authenticated-looking requests to your server from a visitor's browser.

How to Fix Common Issues

1. Add HTTPS — deploy your server behind a TLS-terminating reverse proxy such as Cloudflare, Nginx, or Caddy. Cloudflare's free plan handles this with zero config.
2. Require authentication — add a Bearer token check for internal tools (5 minutes to implement) or full OAuth 2.1 with PKCE for public-facing servers.
3. Add HSTS — set the Strict-Transport-Security: max-age=31536000 header in your server's response or in your reverse proxy config.
4. Restrict CORS — replace * with your specific allowed origins, e.g. https://claude.ai or your application domain.
5. Add remaining headers — X-Content-Type-Options: nosniff and X-Frame-Options: SAMEORIGIN can be added in a single middleware or proxy config block.

For step-by-step implementation with code examples, read our guide on securing MCP servers with OAuth 2.1, Bearer tokens, and Cloudflare Access.