The Notes Remote Procedure Call (NRPC) protocol in IBM Lotus Notes Domino before 6.5.5 FP2 and 7.x before 7.0.2 does not require authentication to perform user lookups, which allows remote attackers to obtain the user ID file.
https://exchange.xforce.ibmcloud.com/vulnerabilities/30118
https://euvd.enisa.europa.eu/vulnerability/EUVD-2006-5819
http://www.vupen.com/english/advisories/2006/4411
http://www.securityfocus.com/bid/20960
http://www.fortconsult.net/images/pdf/lotusnotes_keyfiles.pdf
http://www-1.ibm.com/support/docview.wss?rs=463&uid=swg21248026