Wagtail CMS 6.4.1 is vulnerable to a Stored Cross-Site Scripting (XSS) in the document upload functionality. Attackers can inject malicious code inside a PDF file. When a user clicks the document in the CMS interface, the payload executes. NOTE: this is disputed by the Supplier because "It has been well documented that when serving uploaded files using a method outside of Wagtail (which admittedly is the default), it requires additional configuration from the developer, because Wagtail cannot control how these are served. ... For example, if a Wagtail instance is configured to upload files into AWS S3, Wagtail cannot control the permissions on how they're served, nor any headers used when serving them (a limitation of S3)."
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.