A heap corruption of type CWE-120 exists in quassel version 0.12.4 in quasselcore in void DataStreamPeer::processMessage(const QByteArray &msg) datastreampeer.cpp line 62 that allows an attacker to execute code remotely.
https://www.debian.org/security/2018/dsa-4189
https://usn.ubuntu.com/4594-1/
https://security.gentoo.org/glsa/201806-04
https://lists.debian.org/debian-lts-announce/2018/05/msg00001.html