A Denial Of Service vulnerability in MiniUPnP MiniUPnPd through 2.1 exists due to a NULL pointer dereference in copyIPv6IfDifferent in pcpserver.c.
https://www.vdoo.com/blog/security-issues-discovered-in-miniupnp
https://usn.ubuntu.com/4542-1/
https://lists.debian.org/debian-lts-announce/2019/05/msg00045.html
https://github.com/miniupnp/miniupnp/commit/cb8a02af7a5677cf608e86d57ab04241cf34e24f