silverstripe-asset-admin is a silverstripe assets gallery for asset management. When using the "insert media" functionality, the linked oEmbed JSON includes an HTML attribute which will replace the embed shortcode. The HTML is not sanitized before replacing the shortcode, allowing a script payload to be executed on both the CMS and the front-end of the website. This issue has been addressed in silverstripe/framework version 5.3.8 and users are advised to upgrade. There are no known workarounds for this vulnerability.