This indicates an attack attempt to exploit a Heap Buffer Overflow vulnerability in Dnsmasq.
The vulnerability is due to an error when the vulnerable software receives a malformed DNS response. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application.
Dnsmasq versions prior to 2.78
System Compromise: Remote attackers can gain control of vulnerable systems.
Upgrade to the latest version available from the website.