API Security
GraphQL API Security: Common Risks and Best Practices
Why GraphQL introduces security problems that REST APIs mostly avoid, and how to test for them.
LOZULA Senior Security Research Team
2026-01-20
8 min read
Key Takeaways for Security Teams
- Query depth limiting is the single highest-value control most GraphQL APIs are missing.
- Introspection should never be reachable in a production environment.
- Authorization needs to be checked per-field, not just per-endpoint.
GraphQL gives clients flexible, single-endpoint access to backend data, which is exactly what also makes it prone to over-fetching, denial-of-service through nested queries, and authorization logic that is easy to get wrong.
Risks Specific to GraphQL
Because GraphQL exposes one flexible endpoint instead of many fixed REST routes, several risk categories are unique to it or far more common in it.
- •Deep query nesting and query batching used to trigger resource-exhaustion denial of service
- •Introspection left enabled in production, revealing the full schema including internal-only fields
- •Field-level authorization gaps, where an object is protected but a nested field on it is not
- •Excessive data exposure from resolvers that return more fields than the client actually requested access to
Practical Mitigations
Most of these risks have well-established, low-friction fixes.
- •Enforce query depth and complexity limits at the gateway layer
- •Disable introspection in production environments
- •Apply authorization checks at the field/resolver level, not just at the top-level query
- •Rate-limit based on computed query cost, not just request count