mcp-server-fuzzer

The MCP Server Fuzzer is designed to generate potentially malicious inputs to find vulnerabilities in target MCP servers. However, the fuzzer itself has a highly robust and layered safety system to protect the host machine where it runs. This includes argument-level sanitization using a DangerDetector (blocking dangerous URLs, script injection, and command patterns), a filesystem sandboxing mechanism that confines file operations to a specified root directory, and a System Command Blocker that installs PATH shims to intercept and prevent the execution of dangerous system commands (like browser launches). Network policy controls (default-deny, allowlists, proxy stripping) further restrict outbound network access. These extensive internal safeguards make the fuzzer itself very safe to run on a host system, even while it's actively trying to exploit vulnerabilities in a target.