The WP Post Author WordPress plugin before 4.2.0 does not check that the account was created before updating its profile during front-end registration, allowing unauthenticated users to overwrite the display name, nickname and website of the first user account, which is normally the administrator, when a registration form declares one of those fields.
https://wpscan.com/vulnerability/605832f7-40d5-4a74-a30a-5f5f2906db63/