Sulu is an open-source PHP content management system based on the Symfony framework. Starting in versions 2.5.21, 2.6.5, and 3.0.0-alpha1, an admin user can upload SVG which may load external data via XML DOM library. This can be used for insecure XML External Entity References. The problem has been patched in versions 2.6.9, 2.5.25, and 3.0.0-alpha3. As a workaround, one may patch the effect file src/Sulu/Bundle/MediaBundle/FileInspector/SvgFileInspector.php manually.
The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.