In ZeroMQ libzmq before 4.0.9, 4.1.x before 4.1.7, and 4.2.x before 4.3.2, a remote, unauthenticated client connecting to a libzmq application, running with a socket listening with CURVE encryption/authentication enabled, may cause a stack overflow and overwrite the stack with arbitrary data, due to a buffer overflow in the library. Users running public servers with the above configuration are highly encouraged to upgrade as soon as possible, as there are no known mitigations.
https://www.debian.org/security/2019/dsa-4477
https://usn.ubuntu.com/4050-1/
https://security.gentoo.org/glsa/201908-17
https://seclists.org/bugtraq/2019/Jul/13
https://news.ycombinator.com/item?id=39970716
https://lists.debian.org/debian-lts-announce/2019/07/msg00007.html
https://github.com/zeromq/libzmq/releases
https://github.com/zeromq/libzmq/issues/3558
http://www.securityfocus.com/bid/109284
http://www.openwall.com/lists/oss-security/2019/07/08/6
http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00033.html