Privilege escalation from view right on XWiki.Notifications.Code.LegacyNotificationAdministration in xwiki-platform

XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. Affected versions of xwiki are subject to code injection in the `since` parameter of the `/xwiki/bin/view/XWiki/Notifications/Code/LegacyNotificationAdministration` endpoint. This provides an XWiki syntax injection attack via the since-parameter, allowing privilege escalation from view to programming rights and subsequent code execution privilege. The vulnerability has been patched in XWiki 15.0-rc-1, 14.10.3, 14.4.8 and 14.10.3. Users are advised to upgrade. Users unable to upgrade may modify the page `XWiki.Notifications.Code.LegacyNotificationAdministration` to add the missing escaping. For versions < 14.6-rc-1 a workaround is to modify the file `<xwikiwebapp>/templates/distribution/eventmigration.wiki` to add the missing escaping.