XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. Users are able to forge an URL with a payload allowing to inject Javascript in the page (XSS). It's possible to exploit the delete template to perform a XSS, e.g. by using URL such as: > xwiki/bin/get/FlamingoThemes/Cerulean?xpage=xpart&vm=delete.vm&xredirect=javascript:alert(document.domain). This vulnerability exists since XWiki 6.0-rc-1. The vulnerability has been patched in XWiki 14.10.6 and 15.1. Note that a partial patch has been provided in 14.10.5 but wasn't enough to entirely fix the vulnerability.
https://jira.xwiki.org/browse/XWIKI-20672
https://jira.xwiki.org/browse/XWIKI-20583
https://jira.xwiki.org/browse/XWIKI-20341
https://github.com/xwiki/xwiki-platform/security/advisories/GHSA-834c-x29c-f42c
https://github.com/xwiki/xwiki-platform/commit/e80d22d193df364b07bab7925572720f91a8984a
https://github.com/xwiki/xwiki-platform/commit/24ec12890ac7fa6daec8d0b3435cfcba11362fd5
https://github.com/xwiki/xwiki-platform/commit/13875a6437d4525ac4aeea25918f2d2dffac9ee1