function allowCrossDomain (req, res, next) {
  res.setHeader('Access-Control-Allow-Origin', '*')
  res.setHeader('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, PATCH, OPTIONS')
  res.setHeader(
    'Access-Control-Allow-Headers',
    'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,accesstoken,X-RToken,X-Token'
  )
  res.setHeader('Content-Security-Policy', "frame-ancestors 'none';")

  if (req.method === 'OPTIONS') {
    res.sendStatus(200)
  } else {
    next()
  }
}
The web application does not restrict or incorrectly restricts frame objects or UI layers that belong to another application or domain, which can lead to user confusion about which interface the user is interacting with.