What are the most common vulnerabilities in GraphQL APIs during a Web Pentest?

All answers to this question.

Even with introspection disabled, you can often "guess" the schema using tools like Clairvoyance. The most common GraphQL-specific vulnerability is the "Circular Query" or "Deep Nesting" attack. Since GraphQL allows you to define the data you want, an attacker can craft a query that requests a user, who has friends, who have friends, and so on, recursively. This can lead to a Denial of Service (DoS) by exhausting the server's CPU and memory. You should also check for "Batching Attacks" where an attacker sends hundreds of queries in a single HTTP request to bypass rate-limiting. In a 2024 audit, we found that many developers forget to implement "Query Cost Analysis," which is the best defense against these resource-exhaustion bugs.

   Answered 2025-10-15 by Amanda Richardson

Does GraphQL suffer from the same "Insecure Direct Object Reference" (IDOR) issues as REST, or does the query structure change how we test for authorization?

   Answered 2025-10-30 by David Harrison

• David, it’s actually more common in GraphQL because of the way objects are nested. It's called "Insecure Field-Level Authorization." You might be authorized to see a User object, but not the Salary field inside it. If the developer didn't put a check on that specific resolver, you can just add the field to your query and steal sensitive data. Always test every single field in a mutation or query for proper permission checks.

     Commented 2025-11-10 by Michael Stevens

Check for "Alias" based DoS too. An attacker can request the same expensive field 500 times using different aliases in one query to crush the database.

   Answered 2025-11-20 by Patricia Adams

• That's a great catch, Patricia. Aliasing is often overlooked by developers focusing on depth. It's an easy way to multiply the load on the backend with a very small payload.

     Commented 2025-11-25 by Michael Thompson