The default login template (/vgn/login) in Vignette StoryServer 5 and Vignette V/5 generates different responses whether a user exists or not, which allows remote attackers to identify valid usernames via brute force attacks.
http://www.securityfocus.com/bid/7691
http://www.s21sec.com/en/avisos/s21sec-020-en.txt