Infopop Ultimate Bulletin Board up to v5.47a was discovered to allow all messages posted inside private forums to be disclosed by unauthenticated users via the quote reply feature.
https://web.archive.org/web/20030207100935/http://www.infopop.com/support/ubbclassic/version5.html
https://web.archive.org/web/20030207100935/
https://vulners.com/securityvulns/SECURITYVULNS:DOC:954