Hugo Dias of the Synchron Security Labs discovered a remote denial of service flaw in the avahi daemon. A crafted multicast DNS (mDNS) packet with source port 0 can trigger assertion in originatesfromlocallegacyunicastsocket() function in avahi-core/server.c -- assert(port > 0); -- causing the daemon to call abort() and exit unexpectedly.

Scope of this attack is usually limited to a single LAN.

The Avahi daemon in Avahi before 0.6.20 allows attackers to cause a denial of service (exit) via empty TXT data over D-Bus, which triggers an assert error.