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.