ISC DHCP 4.1.x before 4.1-ESV-R13 and 4.2.x and 4.3.x before 4.3.4 does not restrict the number of concurrent TCP sessions, which allows remote attackers to cause a denial of service (INSIST assertion failure or request-processing outage) by establishing many sessions.

libdns in ISC DHCP 4.2.x before 4.2.5-P1 allows remote name servers to cause a denial of service (memory consumption) via vectors involving a regular expression, as demonstrated by a memory-exhaustion attack against a machine running a dhcpd process, a related issue to CVE-2013-2266.

Multiple memory leaks in ISC DHCP 4.1.x and 4.2.x before 4.2.4-P1 and 4.1-ESV before 4.1-ESV-R6 allow remote attackers to cause a denial of service (memory consumption) by sending many requests.

ISC DHCP 4.1.2 through 4.2.4 and 4.1-ESV before 4.1-ESV-R6 allows remote attackers to cause a denial of service (infinite loop and CPU consumption) via a malformed client identifier.

Buffer overflow in ISC DHCP 4.2.x before 4.2.4-P1, when DHCPv6 mode is enabled, allows remote attackers to cause a denial of service (segmentation fault and daemon exit) via a crafted client identifier parameter.

The logging functionality in dhcpd in ISC DHCP before 4.2.3-P2, when using Dynamic DNS (DDNS) and issuing IPv6 addresses, does not properly handle the DHCPv6 lease structure, which allows remote attackers to cause a denial of service (NULL pointer dereference and daemon crash) via crafted packets related to a lease-status update.

dhcpd in ISC DHCP 4.x before 4.2.3-P1 and 4.1-ESV before 4.1-ESV-R4 does not properly handle regular expressions in dhcpd.conf, which allows remote attackers to cause a denial of service (daemon crash) via a crafted request packet.

The server in ISC DHCP 3.x and 4.x before 4.2.2, 3.1-ESV before 3.1-ESV-R3, and 4.1-ESV before 4.1-ESV-R3 allows remote attackers to cause a denial of service (daemon exit) via a crafted BOOTP packet.

The server in ISC DHCP 3.x and 4.x before 4.2.2, 3.1-ESV before 3.1-ESV-R3, and 4.1-ESV before 4.1-ESV-R3 allows remote attackers to cause a denial of service (daemon exit) via a crafted DHCP packet.

dhclient in ISC DHCP 3.0.x through 4.2.x before 4.2.1-P1, 3.1-ESV before 3.1-ESV-R1, and 4.1-ESV before 4.1-ESV-R2 allows remote attackers to execute arbitrary commands via shell metacharacters in a hostname obtained from a DHCP message, as demonstrated by a hostname that is provided to dhclient-script.

The DHCPv6 server in ISC DHCP 4.0.x and 4.1.x before 4.1.2-P1, 4.0-ESV and 4.1-ESV before 4.1-ESV-R1, and 4.2.x before 4.2.1b1 allows remote attackers to cause a denial of service (assertion failure and daemon crash) by sending a message over IPv6 for a declined and abandoned address.

ISC DHCP server 4.0 before 4.0.2, 4.1 before 4.1.2, and 4.2 before 4.2.0-P1 allows remote attackers to cause a denial of service (NULL pointer dereference and crash) via a DHCPv6 packet containing a Relay-Forward message without an address in the Relay-Forward link-address field.