Hi,
As part of some research that I'm doing in the Mongolian Wikipedia, I found an administrator account called Доромжлол шүүгч that doesn't have anything in Special:Contributions, or any log entries.
It appears as a red link on https://mn.wikipedia.org/wiki/Special:ListUsers/sysop .
Perhaps it's not a usual kind of a security issue, but I couldn't think of a better way to report it.