Decidim is a participatory democracy framework. Starting in version 0.23.0 and prior to versions 0.27.5 and 0.28.0, the CSRF authenticity token check is disabled for the questionnaire templates preview. The issue does not imply a serious security thread as you need to have access also to the session cookie in order to see this resource. This URL does not allow modifying the resource but it may allow attackers to gain access to information which was not meant to be public. The issue is fixed in version 0.27.5 and 0.28.0. As a workaround, disable the templates functionality or remove all available templates.
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.