In Eclipse Mosquitto version from 1.0 to 1.4.15, a Null Dereference vulnerability was found in the Mosquitto library which could lead to crashes for those applications using the library.
https://lists.debian.org/debian-lts-announce/2021/10/msg00022.html
https://lists.debian.org/debian-lts-announce/2019/10/msg00035.html