XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. Any user with view rights can execute arbitrary script macros including Groovy and Python macros that allow remote code execution including unrestricted read and write access to all wiki contents. The attack works by opening a non-existing page with a name crafted to contain a dangerous payload. This issue has been patched in XWiki 14.4.8, 14.10.3 and 15.0RC1. Users are advised to upgrade. There are no known workarounds for this vulnerability.