XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. XWiki Platform Legacy Old Core and XWiki Platform Old Core versions 1.1 through 16.4.6, 16.5.0-rc-1 through 16.10.4 and 17.0.0-rc-1 through 17.1.0, the XML export of a page in XWiki that can be triggered by any user with view rights on a page by appending ?xpage=xml to the URL includes password and email properties stored on a document that aren't named password or email. This is fixed in versions 16.4.7, 16.10.5 and 17.2.0-rc-1. To work around this issue, the file templates/xml.vm in the deployed WAR can be deleted if the XML isn't needed. There isn't any feature in XWiki itself that depends on the XML export.
The product does not properly prevent a person's private, personal information from being accessed by actors who either (1) are not explicitly authorized to access the information or (2) do not have the implicit consent of the person about whom the information is collected.