An issue was discovered in Icinga 2.x through 2.8.1. By sending specially crafted (authenticated and unauthenticated) requests, an attacker can exhaust a lot of memory on the server side, triggering the OOM killer.
etc/initsystem/prepare-dirs in Icinga 2.x through 2.8.1 has a chown call for a filename in a user-writable directory, which allows local users to gain privileges by leveraging access to the $ICINGA2USER account for creation of a link.