XWiki Rendering is a generic rendering system that converts textual input in a given syntax (wiki syntax, HTML, etc) into another syntax (XHTML, etc). Prior to versions 14.10.2 and 15.0 RC1, any user who can edit their own user profile or any other document can execute arbitrary script macros including Groovy and Python macros that allow remote code execution including unrestricted read and write access to all wiki contents. The reason is that rendering output is included as content of HTML macros without further escaping and it is thus possible to close the HTML macro and inject script macros that are executed with programming rights. This has been patched in XWiki 14.10.2 and 15.0 RC1 by making sure that rendering output cannot close the surrounding HTML macro. A possible workaround is available. It is, in principle, possible to add escaping to all places where rendering output is used in wiki documents, but at the moment there is no list of them.