A specially crafted URL with an '@' sign but empty user info and no hostname, when parsed with url-parse, url-parse will return the incorrect href. In particular,

parse(\"http://@/127.0.0.1\")

Will return:

{
 slashes: true,
 protocol: 'http:',
 hash: '',
 query: '',
 pathname: '/127.0.0.1',
 auth: '',
 host: '',
 port: '',
 hostname: '',
 password: '',
 username: '',
 origin: 'null',
 href: 'http:///127.0.0.1'
 }

If the 'hostname' or 'origin' attributes of the output from url-parse are used in security decisions and the final 'href' attribute of the output is then used to make a request, the decision may be incorrect.