Earlier today, I was trying to set up fastcgi caching for guest visitors to see pages more quickly. See: XenForo Forum with Nginx fastcgi_cache full page guest caching Somehow that resulted in some members here at FujiXspot and also at another site (TalkEmount) to be briefly logged in as other members. There was at least one case of a member posting accidentally under someone else's account. It is possible that some members could have read someone else's PMs and/or viewed their email addresses and birthdates. They would not have been able to access passwords. The situation was fixed within about an hour after it was reported.