Remote code execution through the section parameter in Administration as guest in XWiki Platform

XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. XWiki doesn't properly escape the section URL parameter that is used in the code for displaying administration sections. This allows any user with read access to the document XWiki.AdminSheet (by default, everyone including unauthenticated users) to execute code including Groovy code. This impacts the confidentiality, integrity and availability of the whole XWiki instance. This vulnerability has been patched in XWiki 14.10.14, 15.6 RC1 and 15.5.1. Users are advised to upgrade. Users unablr to upgrade may apply the fix in commit fec8e0e53f9 manually. Alternatively, to protect against attacks from unauthenticated users, view right for guests can be removed from this document (it is only needed for space and wiki admins).