function makeError(msg, level, fatal) {
  const err = new Error(msg);
  if (typeof level === 'boolean') {
    fatal = level;
    err.level = 'protocol';
  } else {
    err.level = level || 'protocol';
  }
  err.fatal = !!fatal;
  return err;
}
The software constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.