Firefly III user API endpoints expose all users' information to any authenticated user (IDOR)

Summary

The User management API endpoints (GET /api/v1/users and GET /api/v1/users/{id}) are accessible to any authenticated user without admin/owner role verification, exposing all users' email addresses, roles, and account status.

Affected Endpoints

1. GET /api/v1/users (UserController::index, line 94) — Lists ALL users with full details. No role check.
2. GET /api/v1/users/{id} (UserController::show, line 126) — Shows any user's details by ID. No role check.

Root Cause (1-of-N Inconsistency)

Other methods in the same controller properly check for the 'owner' role:

• store() — UserStoreRequest::authorize() checks auth()->user()->hasRole('owner') ✓
• destroy() — Explicitly checks $this->repository->hasRole($admin, 'owner') ✓

But index() and show() have no role check at all. The route group at routes/api.php:734-747 has no admin middleware, only the global auth:api middleware.

Exposed Data

The UserTransformer (line 40-54) returns:

• email — user's email address
• role — user's role (owner/demo)
• blocked — account blocked status
• blocked_code — block reason
• created_at / updated_at — timestamps

Impact

Any authenticated user can:

1. Enumerate ALL user accounts in the instance
2. Harvest email addresses for phishing/social engineering
3. Identify admin/owner accounts by role
4. Determine which accounts are blocked

Exploitation

# List all users
curl -H "Authorization: Bearer <any_user_token>" https://instance/api/v1/users

# View specific user details
curl -H "Authorization: Bearer <any_user_token>" https://instance/api/v1/users/1

Suggested Fix

Add owner role checks to index() and show(), or restrict the route group with admin middleware:

// Option 1: Add check in controller methods
public function show(User $user): JsonResponse
{
    if (!$this->repository->hasRole(auth()->user(), 'owner') && auth()->user()->id !== $user->id) {
        throw new FireflyException('200025: No access to function.');
    }
    // ...
}

// Option 2: Add middleware to route group
Route::group(['middleware' => ['admin'], ...], ...)