The XWiki Platform Index UI is an Index of all pages, attachments, orphans and deleted pages and attachments for XWiki Platform, a generic wiki platform. Prior to versions 13.10.6 and 14.3, it's possible to store JavaScript which will be executed by anyone viewing the deleted attachments index with an attachment containing javascript in its name. This issue has been patched in XWiki 13.10.6 and 14.3. As a workaround, modify fix the vulnerability by editing the wiki page `XWiki.DeletedAttachments` with the object editor, open the `JavaScriptExtension` object and apply on the content the changes that can be found on the fix commit.