XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. It's possible to perform an XSS by forging a request to a delete attachment action with a specific attachment name. Now this XSS can be exploited only if the attacker knows the CSRF token of the user, or if the user ignores the warning about the missing CSRF token. The vulnerability has been patched in XWiki 15.1-rc-1 and XWiki 14.10.6.
https://jira.xwiki.org/browse/XWIKI-20339
https://github.com/xwiki/xwiki-platform/security/advisories/GHSA-phwm-87rg-27qq
https://github.com/xwiki/xwiki-platform/commit/35e9073ffec567861e0abeea072bd97921a3decf