In WordPress before 4.9.9 and 5.x before 5.0.1, the user-activation page could be read by a search engine’s web crawler if an unusual configuration were chosen. The search engine could then index and display a user’s e-mail address and (rarely) the password that was generated by default.
www.securityfocus.com/bid/106220
codex.wordpress.org/Version_4.9.9
lists.debian.org/debian-lts-announce/2019/02/msg00019.html
wordpress.org/news/2018/12/wordpress-5-0-1-security-release/
wordpress.org/support/wordpress-version/version-5-0-1/
wpvulndb.com/vulnerabilities/9174
www.debian.org/security/2019/dsa-4401
www.zdnet.com/article/wordpress-plugs-bug-that-led-to-google-indexing-some-user-passwords/