CVE-2021-40109
A SSRF issue was discovered in Concrete CMS through 8.5.5. Users can access forbidden files on their local network. A user with permissions to upload files from external sites can upload a URL that redirects to an internal resource of any file type. The redirect is followed and loads the contents of the file from the redirected-to server. Files of disallowed types can be uploaded.
Date published : 2021-09-27
https://documentation.concretecms.org/developers/introduction/version-history/856-release-notes