Fix BOLA (Broken Object Level Authorization) in Buffalo

BOLA (Broken Object Level Authorization) is the most critical vulnerability in modern API-centric applications. In the Buffalo framework, it occurs when a handler retrieves a record from the database using a user-supplied ID from the URL (e.g., /widgets/{id}) without verifying if the authenticated user has the rights to access that specific record. If you aren't scoping your Pop queries to the session user, you're leaking data.

The Vulnerable Pattern

func (v WidgetsResource) Show(c buffalo.Context) error {
  widget := &models.Widget{}
  // VULNERABLE: Directly fetching by ID from the URL parameter.
  // Any authenticated user can guess an ID and access any widget.
  if err := models.DB.Find(widget, c.Param("widget_id")); err != nil {
    return c.Error(404, err)
  }
  return c.Render(200, r.JSON(widget))
}

The Secure Implementation

To kill BOLA in Buffalo, you must abandon the convenience of simple ID-based lookups like 'DB.Find(id)'. Instead, use the 'Where' clause to enforce ownership at the database layer. By including the 'user_id' (extracted from a trusted session or JWT) in every query, you ensure that the database only returns records belonging to the requester. If a user attempts to access an ID they don't own, the query returns no results, effectively neutralizing the authorization bypass.

func (v WidgetsResource) Show(c buffalo.Context) error {
  // SECURE: Retrieve the user ID from the session or context
  currentUserID := c.Session().Get("current_user_id")
  widget := &models.Widget{}
// SECURE: Scope the query to both the Object ID AND the User ID
query := models.DB.Where(“id = ? AND user_id = ?”, c.Param(“widget_id”), currentUserID)
if err := query.First(widget); err != nil {
// Return 404 or 403 to prevent ID enumeration
return c.Error(403, fmt.Errorf(“Unauthorized or Not Found”))
}
return c.Render(200, r.JSON(widget))
}