Lotus Sametime suffers from a user enumeration vulnerability. This is based on the time it takes to respond when authenticating credentials. IBM Lotus Instant Messaging and Web Conferencing (Sametime) version 6.5.1 is affected.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/79044/lotus-enumerate.txt
Source: https://packetstormsecurity.com/files/79044/Lotus-Sametime-User-Enumeration.html