XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. In affected versions of XWiki Platform, the `{{wikimacrocontent}}` executes the content with the rights of the wiki macro author instead of the caller of that wiki macro. This makes possible to inject scripts through it and they will be executed with the rights of the wiki macro (very often a user which has Programming rights). Fortunately, no such macro exists by default in XWiki Standard but one could have been created or installed with an extension. This vulnerability has been patched in versions XWiki 12.6.3, 11.10.11 and 12.8-rc-1. There is no easy workaround other than disabling the affected macros. Inserting content in a safe way or knowing what is the user who called the wiki macro is not easy.
In XWiki before version 12.5 and 11.10.6, any user with SCRIPT right (EDIT right before XWiki 7.4) can gain access to the application server Servlet context which contains tools allowing to instantiate arbitrary Java objects and invoke methods that may lead to arbitrary code execution. This is patched in XWiki 12.5 and XWiki 11.10.6.
In XWiki before versions 11.10.5 or 12.2.1, any user with SCRIPT right (EDIT right before XWiki 7.4) can gain access to the application server Servlet context which contains tools allowing to instantiate arbitrary Java objects and invoke methods that may lead to arbitrary code execution. The only workaround is to give SCRIPT right only to trusted users.
In XWiki Platform 7.2 through 11.10.2, registered users without scripting/programming permissions are able to execute python/groovy scripts while editing personal dashboards. This has been fixed 11.3.7 , 11.10.3 and 12.0.