XWiki Platform is a generic wiki platform. Starting in version 2.3 and prior to versions 15.10.9, 16.3.0, any user with script rights can perform arbitrary remote code execution by adding instances of XWiki.ConfigurableClass
to any page. This compromises the confidentiality, integrity and availability of the whole XWiki installation. This has been patched in XWiki 15.10.9 and 16.3.0. No known workarounds are available except upgrading.