The Dynamic Host Configuration Protocol is a protocol that allows individual devices on an IP network to get their own network configuration information, including an IP address, a subnet mask, and a broadcast address. DHCPv6 is the DHCP protocol version for IPv6 networks. A flaw was found in the way the dhcpd daemon processed certain DHCPv6 messages for addresses that had previously been declined and marked as abandoned internally. If a remote attacker sent such messages to dhcpd, it could cause dhcpd to crash due to an assertion failure if it was running as a DHCPv6 server. Red Hat would like to thank Internet Systems Consortium for reporting this issue. Users running dhcpd as a DHCPv6 server should upgrade to these updated packages, which contain a backported patch to correct this issue. After installing this update, all DHCP servers will be restarted automatically.