CVE-2024-55662: XWiki allows remote code execution through the extension sheet

On instances where Extension Repository Application is installed, any user can execute any code requiring programming rights on the server. In order to reproduce on an instance, as a normal user without script nor programming rights, go to your profile and add an object of type ExtensionCode.ExtensionClass. Set the description to {{async}}{{groovy}}println("Hello from Description"){{/groovy}}{{/async}} and press Save and View. If the description displays as Hello from Description without any error, then the instance is vulnerable.