The onReadyRead function in core/coreauthhandler.cpp in Quassel before 0.12.4 allows remote attackers to cause a denial of service (NULL pointer dereference and crash) via invalid handshake data.
lists.opensuse.org/opensuse-updates/2016-05/msg00063.html
quassel-irc.org/node/129
www.openwall.com/lists/oss-security/2016/04/30/2
www.openwall.com/lists/oss-security/2016/04/30/4
github.com/quassel/quassel/commit/e678873
lists.fedoraproject.org/pipermail/package-announce/2016-May/183571.html
lists.fedoraproject.org/pipermail/package-announce/2016-May/183585.html
lists.fedoraproject.org/pipermail/package-announce/2016-May/183746.html