XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. It's possible to make the farm unusable by adding an object to a page with a huge number (e.g. 67108863). Most of the time this will fill the memory allocated to XWiki and make it unusable every time this document is manipulated. This issue has been patched in XWiki 14.0-rc-1.
XWiki Platform is a generic wiki platform. Starting in version 1.3-rc-1, any user with edit right can execute arbitrary database select and access data stored in the database. The problem has been patched in XWiki 13.10.11, 14.4.7, and 14.10. There is no workaround for this vulnerability other than upgrading.
XWiki Platform is a generic wiki platform. Starting in version 13.10, it's possible to use the right of an existing document content author to execute a text area property. This has been patched in XWiki 14.10, 14.4.7, and 13.10.11. There are no known workarounds.
XWiki Platform is a generic wiki platform. Starting in version 2.3-milestone-1, the annotation displayer does not execute the content in a restricted context. This allows executing anything with the right of the author of any document by annotating the document. This has been patched in XWiki 13.10.11, 14.4.7 and 14.10. There is no easy workaround except to upgrade.