In SilverStripe through 4.5, files uploaded via Forms to folders migrated from Silverstripe CMS 3.x may be put to the default ""/Uploads"" folder instead. This affects installations which allowed upload folder protection via the optional silverstripe/secureassets module under 3.x. This module is installed and enabled by default on the Common Web Platform (CWP). The vulnerability only affects files uploaded after an upgrade to 4.x.
https://www.silverstripe.org/download/security-releases/
https://www.silverstripe.org/download/security-releases/cve-2020-9280
https://forum.silverstripe.org/c/releases
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-9280