Silverstripe Framework Cross-Site Scripting Vulnerability in Asset Admin via oEmbed Shortcode

A cross-site scripting vulnerability has been identified in the Silverstripe Asset Admin component, specifically in versions of the Silverstripe Framework prior to 5.3.8. The issue arises when the 'insert media' feature is used, as the linked oEmbed JSON contains an HTML attribute that replaces the embed shortcode without proper sanitization. This oversight allows script payloads to be executed on both the Content Management System (CMS) and the front end of the website.

Impact

Exploitation of this vulnerability allows for cross-site scripting, where an attacker can inject malicious scripts that are executed in the context of the user.

Reproduction

To reproduce this vulnerability, use the 'insert media' functionality in the Silverstripe Asset Admin. The oEmbed JSON linked to the media will include an HTML attribute that replaces the embed shortcode. Because the HTML is not sanitized, a script payload can be injected and executed on both the CMS and the website's front end.

Remediation

Users are advised to upgrade to Silverstripe Framework version 5.3.8 or later.