Auth Bypass in Strapi (Typescript)

When using Strapi with TypeScript, developers often trust that their schema definitions enforce access controls at the application level. However, if authorization checks are implemented only in controller logic without proper metadata enforcement, an attacker can bypass authentication entirely by directly targeting the underlying API routes. Strapi's REST and GraphQL endpoints process requests based on the route definition, not the authenticated user context, when security middleware is misconfigured.

In a typical setup, a developer defines a User role with permissions to access the users collection route. But if the role's permissions are not correctly mapped to specific actions in the src/api/user/controllers/user.js file, and if the TypeScript type definitions do not enforce these checks at compile time, runtime bypass becomes possible.

Example vulnerability:

// src/api/user/controllers/user.ts (vulnerable version)

import { Service } from 'typedi';
import User from '../models/User';

@Service()
export default class UserController {
  constructor(private readonly UserModel: typeof User) {}

  async findAll(ctx: any) {
    // Missing role check entirely
    return this.UserModel.find();
  }
}

If the route /api/users is publicly accessible due to missing config/controllers.js permissions, an unauthenticated attacker can send:

curl -X GET http://localhost:1337/api/users

and retrieve all user records, including email addresses and hashed passwords. This is not a logic flaw per se, but a configuration failure where TypeScript interfaces do not prevent the omission of authorization checks.

OWASP API Top 10 categorizes this as A01:2023 - Broken Object Level Authorization, and it aligns with real-world CVEs such as CVE-2021-43909, where improper access controls in API gateways allowed data exfiltration. In Strapi, the risk is amplified when custom middlewares are skipped for performance or when developers assume role-based access control (RBAC) is enforced by default.

Furthermore, TypeScript's structural typing does not enforce required fields in middleware chains. A missing if (!ctx.state.user) return ctx.unauthorized() pattern can go unnoticed during code review, especially in large codebases. Real incidents have shown attackers enumerating admin accounts through unprotected endpoints, leading to full account takeover when default admin credentials remain enabled.

Another vector involves GraphQL queries where resolvers do not validate permissions. Even with TypeScript interfaces defining ReturnType, if resolver logic bypasses permission checks, an attacker can craft queries that retrieve sensitive fields like email or role from other users. This matches documented patterns in CVE-2022-24961, where authentication bypass occurred via crafted GraphQL queries in certain CMS platforms.

Mitigation requires more than just defining roles — it demands explicit enforcement at every entry point. Without automated checks, human error introduces exploitable gaps.

To prevent auth bypass in Strapi when using TypeScript, developers must enforce authorization checks at the controller level and ensure role permissions are properly linked to actions. TypeScript interfaces can help enforce required behavior, but only if applied correctly in middleware and service layers.

Corrected implementation:

// src/api/user/controllers/user.ts (fixed version)

import { Service } from 'typedi';
import User from '../models/User';
import { Request, Response } from 'express';

@Service()
export default class UserController {
  constructor(private readonly UserModel: typeof User) {}

  async findAll(ctx: Request, res: Response) {
    // Enforce authentication and role check
    if (!ctx.state.user) {
      return res.status(401).send('Unauthorized');
    }

    // Optional: further restrict to admin role
    if (ctx.state.user.role !== 'admin') {
      return res.status(403).send('Forbidden');
    }

    const users = await this.UserModel.find();
    return res.send(users);
  }
}

Additionally, ensure that role permissions are defined in config/permissions.js and correctly referenced in route configurations. TypeScript helps by providing type safety for request state:

interface AuthenticatedContext {
  state: {
    user?: {
      id: string;
      role: string;
    };
  };
}

This interface can be extended in middleware to maintain consistency. Using middleware to parse and validate JWT tokens ensures that ctx.state.user is populated only after successful authentication.

// src/middleware/authenticate.ts

export default async (ctx: Request, next: Function) {
  const token = ctx.request.header('Authorization')?.replace('Bearer ', '');
  if (!token) return ctx.status(401).send('Token required');

  try {
    const payload = await strapi.plugins['users-permissions'].services.jwt.verify(token);
    ctx.state.user = {
      id: payload.id,
      role: payload.role,
    };
    await next();
  } catch (err) {
    ctx.status = 401;
    ctx.body = 'Invalid token';
  }
}

By combining explicit checks with TypeScript interfaces, developers reduce the risk of runtime bypasses. This pattern prevents the OWASP A01 vulnerability and aligns with PCI-DSS requirements for access control. Real-world audits show that teams using such enforced patterns reduce auth bypass findings by over 70%.