ejabberd before 2.1.13 does not enforce the starttls_required setting when compression is used, which causes clients to establish connections without encryption.
advisories.mageia.org/MGASA-2014-0417.html
mail.jabber.org/pipermail/operators/2014-October/002438.html
seclists.org/oss-sec/2014/q4/312
www.mandriva.com/security/advisories?name=MDVSA-2014:207
www.mandriva.com/security/advisories?name=MDVSA-2015:175
www.securityfocus.com/bid/70415
bugzilla.redhat.com/show_bug.cgi?id=1153839
github.com/processone/ejabberd/commit/7bdc1151b