MCP Security Playbook (Read This, Monkeys)
Listen, monkeys: MCP is a trust machine. These threats are not theoretical — they are what happens when you skip chapters and ship anyway.
Threat: tool poisoning via descriptions
Mitigation
Allowlist servers, review diffs, separate trust tiers, strip or summarize tool metadata for planners.
Threat: path traversal in tools
Mitigation
path.resolve, enforce root, reject .., deny symlinks escaping root.
Threat: SSRF from HTTP MCP tools
Mitigation
Block private IPs, validate URLs, require explicit egress allowlists per tool.
Threat: secrets in tool outputs
Mitigation
Redact patterns, structured logging, never echo env wholesale.