Launchpad.net

CVE 2018-20151

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.

See the CVE page on Mitre.org for more details.