By performing an advanced search, unauthenticated users can enumerate valid usernames with a single HTTP request on the BEA Plumtree Portal.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/61454/PR06-09.txt
Source: https://packetstormsecurity.com/files/61454/ProCheckUp-Security-Advisory-2006.9.html