404 response should be defined for all GET, PUT, HEAD, and DELETE operations

Description

One or more GET, PUT, HEAD, or DELETE operations are missing the 404 response. All GET, PUT, HEAD, and DELETE operations should have the 404 response defined.

For more details, see RFC 7231.

Example

The following is an example of how this type of risk could look in your API definition:

{
  "/pets": {
    "get": {
      "description": "Returns all pets from the system that the user has access to",
      "produces": [
        "application/json"
      ],
      "responses": {
        "200": {
          "description": "A list of pets.",
          "schema": {
            "type": "array",
            "items": {
              "$ref": "#/definitions/Pet"
            }
          }
        }
      }
    }
  }
}

Possible exploit scenario

Attackers strive to make your APIs behave in an unexpected way to learn more about your system or to cause a data breach. We highly recommend that you minimize any risks and clearly specify the data that your API operations can return for each possible response code.

Remediation

Define 404 responses for all GET, PUT, HEAD, and DELETE operations.

  "/pets": {
    "get": {
      "description": "Returns all pets from the system that the user has access to",
      "produces": [
        "application/json"
      ],
      "responses": {
        "200": {
          "description": "A list of pets",
          "schema": {
            "type": "array",
            "items": {
              "$ref": "#/definitions/Pet"
            }
          }
        }
    "404": {
        "description": "Not found"
        "content": {
            "application/json": {
                "schema": {
                    "$ref": "#/definitions/404"
                }
            }
        }           
      }
    }
  }
}