Safe Software FME Server through 2018.1 creates and enables three additional accounts in addition to the initial administrator account. The passwords to the three accounts are the same as the usernames, which are guest, user, and author. Logging in with these accounts will grant any user the default privilege roles that were also created for each of the accounts.
The product initializes or sets a resource with a default that is intended to be changed by the administrator, but the default is not secure.