Netscape 4.7x allows remote attackers to obtain sensitive information such as the user's login, mailbox location and installation path via Javascript that accesses the mailbox: URL in the document.referrer property.
https://exchange.xforce.ibmcloud.com/vulnerabilities/7417
https://euvd.enisa.europa.eu/vulnerability/EUVD-2001-0730
http://archives.neohapsis.com/archives/bugtraq/2001-06/0014.html