Is your MCP server
open to anyone?
A measurement study of 7,973 live remote MCP servers found that 40.55% expose their tools without any authentication, and that every OAuth server examined in depth had at least one flaw. Check yours in a few seconds.
What the scan checks
- Authenticationtools/list and initialize without credentials, and with an invalid token
- OAuth discovery401 challenge with resource_metadata, Protected Resource Metadata (RFC 9728), authorization server metadata
- OAuth hygienePKCE S256, no plain PKCE, no implicit/password grants, iss in responses (RFC 9207), CIMD vs deprecated DCR
- Browser exposureCORS that reflects any origin, plain HTTP transport
- Tool poisoninghidden instructions in tool descriptions of servers that expose their tools
- Client configsunpinned npx/uvx, known-malicious packages, typosquats, shell commands, plaintext secrets, 0.0.0.0, broad filesystem access
Fix it in minutes
Mandat is open source (Apache-2.0). It adds token checks, a policy on every tool call, human approval for risky actions and a tamper-evident audit log to any MCP server.
npm install -g mandatpip install "mandat[mcp]"npx mandat scan <url>