GraphQL Security Guide for Production APIs

GraphQL's flexibility is both its greatest strength and its biggest security challenge. Unlike REST APIs with fixed endpoints, GraphQL allows clients to construct arbitrary queries. This means attackers can craft deeply nested queries that overwhelm your server, request sensitive fields your UI does not use, or exploit schema introspection to map your entire data model. Securing a GraphQL API requires different strategies than securing REST endpoints.

One of the most critical GraphQL protections is limiting query complexity and depth. Without limits, a malicious query with deeply nested relationships can exponentially increase database operations. Use libraries like graphql-query-complexity or graphql-depth-limit to set maximum query costs and nesting levels. Assign cost values to each field and resolver based on their computational expense. Reject queries that exceed your defined thresholds before they execute.

GraphQL introspection allows anyone to query your schema and discover all available types, fields, and relationships. While useful during development, introspection in production reveals your entire API surface to potential attackers. Disable introspection in production environments by configuring your GraphQL server accordingly. If you need documentation for legitimate API consumers, provide it through a separate developer portal rather than through the live schema.

Implement authentication at the server level, typically through middleware that verifies JWT tokens before the GraphQL resolver runs. Authorization should be implemented at the resolver level, checking permissions for each field and operation. Use a library like graphql-shield to define permission rules declaratively. Never rely on the client to request only authorized fields because any authenticated user could manually construct queries requesting data they should not see.

Validate all GraphQL input arguments using custom scalars or input validation libraries. While GraphQL's type system provides basic type checking, it does not prevent injection attacks within valid types. A string argument could still contain SQL injection or NoSQL injection payloads. Sanitize inputs before passing them to database queries. Use parameterized queries in your resolvers rather than string concatenation.

Apply rate limiting to your GraphQL endpoint based on query complexity rather than simple request counts. A simple query should cost less against your rate limit than a complex one. For maximum security, implement persisted queries where only pre-approved queries stored on the server can be executed. This prevents arbitrary query construction entirely. Persisted queries also improve performance since the server does not need to parse and validate queries at runtime.

GraphQL security requires specialized knowledge that differs significantly from REST API security. AI-generated GraphQL code almost never includes query complexity limits, introspection disabling, or field-level authorization. SpringCode reviews GraphQL APIs with a focus on these unique attack vectors, implementing comprehensive protections that let you ship a flexible API without compromising security.