There is XSS in SilverStripe CMS before 3.4.4 and 3.5.x before 3.5.2. The attack vector is a page name. An example payload is a crafted JavaScript event handler within a malformed SVG element.
https://github.com/advisories/GHSA-xmjh-wjc5-wg4h
https://www.silverstripe.org/download/security-releases/