In the Versioned Files module through 2.0.3 for SilverStripe 3.x, unpublished versions of files are publicly exposed to anyone who can guess their URL. This guess could be highly informed by a basic understanding of the symbiote/silverstripe-versionedfiles source code. (Users who upgrade from SilverStripe 3.x to 4.x and had Versioned Files installed have no further need for this module, because the 4.x release has built-in versioning. However, nothing in the upgrade process automates the destruction of these insecure artefacts, nor alerts the user to the criticality of destruction.)

SilverStripe Versioned Files module Unpublished files are exposed publicly