The HTTPS fallback implementation in Shell In A Box (aka shellinabox) before 2.19 makes it easier for remote attackers to conduct DNS rebinding attacks via the "/plain" URL.
https://github.com/shellinabox/shellinabox/releases/tag/v2.19
https://github.com/shellinabox/shellinabox/issues/355
http://www.openwall.com/lists/oss-security/2015/12/02/7
http://www.openwall.com/lists/oss-security/2015/12/02/6
http://lists.fedoraproject.org/pipermail/package-announce/2016-January/175224.html
http://lists.fedoraproject.org/pipermail/package-announce/2016-January/175117.html