XWiki Platform RCE from account through SearchAdmin

XWiki Platform is a generic wiki platform. Starting in 4.5-rc-1 and prior to versions 14.10.15, 15.5.2, and 15.7-rc-1, the search administration interface doesn't properly escape the id and label of search user interface extensions, allowing the injection of XWiki syntax containing script macros including Groovy macros that allow remote code execution, impacting the confidentiality, integrity and availability of the whole XWiki instance. This attack can be executed by any user who can edit some wiki page like the user's profile (editable by default) as user interface extensions that will be displayed in the search administration can be added on any document by any user. The necessary escaping has been added in XWiki 14.10.15, 15.5.2 and 15.7RC1. As a workaround, the patch can be applied manually applied to the page `XWiki.SearchAdmin`.