CVE-2020-14312

A flaw was found in the default configuration of dnsmasq, as shipped with Fedora and Red Hat Enterprise Linux, where it listens on any interface and accepts queries from addresses outside of its local subnet. In particular, the option local-service is not enabled. Running dnsmasq in this manner may inadvertently make it an open resolver accessible from any address on the internet. This flaw allows an attacker to conduct a Distributed Denial of Service (DDoS) against other systems.

Mitigation

To restrict the DNS server to queries coming from the local subnet, add local-service to your /etc/dnsmasq.conf file or in a file in /etc/dnsmasq.d. A firewall can be configured for additional protection against undesired traffic.