GraphQL APIs face a unique threat landscape: deeply nested queries cause resource exhaustion, introspection exposes entire schemas, and mutation variables carry injection payloads past traditional WAFs. Yet most Go-based GraphQL servers ship with zero security middleware between HTTP and resolver execution.

I introduce GraphQLShield, an open-source Go middleware bringing defense-in-depth to GraphQL APIs through three layers: (1) Static schema analysis detecting cyclic types, missing depth limits, and sensitive field exposure before deployment; (2) Runtime CWE-aware input sanitization catching SQL injection, XSS, command injection, path traversal, and NoSQL injection in GraphQL variables — bridging go-safeinput's MITRE CWE Top 25 coverage to GraphQL; and (3) Resolver code auditing inspired by gosec and cryptoguard-go flagging insecure crypto, hardcoded secrets, and missing auth checks.

A quick demo shows GraphQLShield intercepting 7 attack vectors against a gqlgen API , from SQL injection in mutation variables to depth-based DoS, while legitimate requests pass cleanly. Attendees leave with a zero-dependency Go library covering 14 CWE vulnerability classes across static and runtime analysis.