Privilege Escalation in GraphQL – 1 Shocking Real-World Bug Bounty Exploit

By Satyam Pawale (@hackersatty)

About Me

Hey security enthusiasts! I’m Satyam Pawale, better known in the cybersecurity and bug bounty community as @hackersatty. I specialize in identifying real-world security vulnerabilities in web applications using smart reconnaissance, API testing, and JavaScript analysis and Privilege Escalation. I began my bug bounty journey in 2024 and have been passionate about securing web systems ever since.

Privilege Escalation in GraphQL: How I Gained Unauthorized Admin Access

In the world of modern APIs, GraphQL has become increasingly popular for its flexibility and efficiency. However, this flexibility often comes at the cost of security if not implemented properly. One common issue is where a user with lower privileges is able to perform actions or access data meant for higher-privileged users.

In this detailed blog, I will walk you through a real-life bug bounty scenario where a user with a “finance” role was able to exploit GraphQL endpoints to gain unauthorized access to admin data. This exploit highlights critical lapses in role-based access control (RBAC) and shows why it’s essential to validate permissions at every level of API design.

What is Privilege Escalation in GraphQL?

Privilege escalation in GraphQL typically refers to an attacker manipulating queries or tokens in a way that allows them to gain access to data or functionality beyond what their role should permit. This usually happens because of misconfigured access control on the backend or poor handling of user roles within queries and mutations.

GraphQL schemas expose a lot of information through introspection. If the API isn’t properly locked down, a user can query for schema metadata, discover sensitive fields, and craft malicious queries even with a low-privilege token.

Background: The Application I Tested

The application was a business management platform with GraphQL-based APIs. Users were segmented by roles: admin, finance, operations, and customer support. The finance role was intended only to view transaction reports and generate invoices. The admin role, on the other hand, had access to user management, product creation, and system configurations.

Endpoints: 

Privilege Escaltion:

1. Admin
2. Finance

• /graphql

• /graphql.json

• Custom aliases such as /ggql

My role: finance (using a test account). (Privilege Escalation on admin )

Step-by-Step Exploitation

Step 1: GraphQL Endpoint Discovery

First, I identified the GraphQL endpoints using common paths:

• /graphql returned a working GraphQL interface

• Using tools like Postman and InQL, I discovered that introspection was enabled

I downloaded the entire schema and noted down all queries and mutations.

Step 2: Sensitive Mutation Discovery

One mutation drew my attention:

mutation CreateProduct($id: String!, $name: String!) {
  createProduct(id: $id, name: $name) {
    id
    name
    createdBy
  }
}

This was clearly meant for the admin role. It allowed the creation of a product in the system.

Step 3: Capture an Admin Request (Simulated)

Using a test admin account, I observed the request sent for creating a product. It included:

• Authorization: Bearer adminToken

• GraphQL mutation with product ID and name

Step 4: Replace Admin Token with Finance Token

I replaced the admin token with a valid finance user token and replayed the exact same mutation.

To my surprise, the request was successful.

Why did this happen? The backend didn’t validate if the user role matched the operation being performed. The server simply checked if the token was valid, not if the token belonged to a user with the correct privileges.

Real-World Impact of the Exploit

This vulnerability had serious implications:

• The finance user could create products without proper authorization.

• They could potentially access audit logs, admin reports, and user data.

• In an extended scenario, this could be chained with other vulnerabilities to gain full system compromise.

This is not a theoretical issue. Many real-world applications using GraphQL face similar issues due to:

• Missing server-side role validation

• Over-exposed GraphQL schemas

• Poorly implemented authorization layers

Root Cause Analysis : Privilege Escalation

1. Missing Role Check: The createProduct mutation lacked any server-side validation for the user’s role. It assumed the frontend would hide or restrict access.

2. Overuse of Trust in JWTs: While the JWT tokens were valid, the claims within them weren’t checked during sensitive operations. For example, role=finance should have triggered a denial response.

3. Exposed Introspection Schema: This allowed discovery of mutations that shouldn’t have been publicly visible.

Mitigation Strategies

1. Implement Strong Role-Based Access Control (RBAC)

Every query and mutation must validate the user’s role before processing.

if (user.role !== 'admin') {
  throw new Error('Unauthorized');
}

Don’t rely solely on frontend validation.

2. Disable Introspection in Production

Use middleware to block schema introspection in production environments.

const { graphqlHTTP } = require('express-graphql');
graphqlHTTP({
  schema,
  graphiql: false,
  customFormatErrorFn: () => null,
});

3. Enforce Field-Level Authorization

Instead of protecting only at the endpoint or mutation level, ensure that each field in your schema is protected.

4. Audit and Monitor

Set up logging and monitoring on sensitive queries. Alert on:

• Role misuse

• Excessive replayed queries

• Field access patterns

5. Use Allowlists

Only allow access to a predefined list of queries or mutations based on roles. Tools like Hasura or custom middleware can help enforce this.

Key Lessons for Bug Bounty Hunters

• Always inspect GraphQL introspection results for overlooked fields and mutations.

• Try swapping valid tokens across roles to test access control flaws and hunt of Privilege Escalation

• Just because a mutation is hidden on the frontend doesn’t mean it can’t be accessed.

• Combine escalation with IDOR or insecure object references to expand the impact.

Final Thoughts

This bug was simple but devastating. It highlights why GraphQL applications need strict backend validation and continuous security review. Developers often rely on frontend controls or incomplete middleware, assuming it will prevent abuse. However, security must always be enforced server-side.

As a bug bounty hunter, your job is to think creatively. Ask questions like:

• What if I change the token?

• What if I access the mutation directly?

• What if I modify hidden fields?

GraphQL gives attackers power. Make sure your security matches that power.

External Links :

• Graphql

• Owasp-Graphql

• Portswigger-Burp

• Privilege Escalation

Final Thoughts: Keep Hunting, Keep Learning

This was one of my earliest critical bug bounty finds and taught me that Graphql APIs are one of the most vulnerable attack surfaces today. With tools like Swagger, Postman, and Burp Suite at your disposal, you don’t need to brute force—just observe and test logically.

🔍 Graphql API is more than headers and tokens—it’s about understanding how developers structure access and how attackers think. 

If you found this write-up helpful, feel free to connect with me on LinkedIn or follow my work on Twitter.

Until next time, stay curious and stay secure! 🔐