Gallagher Controller 6000 is vulnerable to a Denial of Service attack via conflicting ARP packets with a duplicate IP address. This issue affects: Gallagher Gallagher Controller 6000 vCR8.60 versions prior to 220303a; vCR8.50 versions prior to 220303a; vCR8.40 versions prior to 220303a; vCR8.30 versions prior to 220303a.