- Services 1.x versions prior to 1.x-3.0.4-beta
This module provides a standardized solution for building API's so that external clients can communicate with Backdrop.
The Services module has an access bypass vulnerability in its "attach_file" resource that allows users who have access to create or update pieces of content that include file fields to arbitrarily reference files they do not have access to, which can expose private files.
This vulnerability is mitigated by the fact that an attacker must have a role with permission to create or edit a piece of content.
- Samuel Mortenson of the Drupal Security Team