Horde Trean, as used in Horde Groupware Webmail Edition through 5.2.22 and other products, allows CSRF, as demonstrated by the treanBookmarkTags parameter to the trean/ URI on a webmail server. NOTE: treanBookmarkTags could, for example, be a stored XSS payload.
https://lists.debian.org/debian-lts-announce/2019/12/msg00015.html