Array header with string items has no maximum length defined

Average severity: Medium

Description

An array header containing string items does not define the maximum length for the accepted strings.

Example

The following is an example of how this type of risk could look in your API definition. The array header accepts items of the type string of unlimited length:

"responses": {
  "200": {
    "description": "OK",
    "headers": {
      "x-ids": {
        "schema": {
          "type": "array",
            "items": {
            "type": "string"
          }
        }
      }
    }
  }
}

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 produces in each method.

Remediation

Set the maxLength property in array headers with string items. This provides an extra layer of safety ensuring that your API only returns data that you expect it to return.

"responses": {
  "200": {
    "description": "OK",
    "headers": {
      "x-ids": {
        "schema": {
          "type": "array",
          "items": {
            "type": "string",
            "maxLength": "8"
          }
        }
      }
    }
  }
}

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