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.