A vulnerability was found in DHCP, where, a system with access to a DHCP server, sending DHCP packets crafted to include "fqdn" labels longer than 63 bytes, could eventually cause the server to run out of memory.

Versions affected:

- 1.0.0 -> 4.1-ESV-R16-P1 - 4.2.0 -> 4.4.3

A vulnerability was found in DHCP, where, a DHCP server configured with "allow leasequery;", a remote machine with access to the server can send lease queries for the same lease multiple times, leading to the "addoption()" function being repeatedly called. This could cause an option's "refcount" field to overflow and the server to abort. Internally, reference counters are integers and thus overflow at 2^31 references, so even at 1000 lease query responses per second, it would take more than three weeks to crash the server.

Versions affected:

- 4.1-ESV-R1 -> 4.1-ESV-R16-P1 - 4.4.0 -> 4.4.3

Other branches of ISC DHCP (i.e., releases in the 4.0.x series or lower and releases in the 4.3.x series), it is probable, all versions after the introduction of lease query in ISC DHCP 3.0 are affected.

A malicious client which is allowed to send very large amounts of traffic (billions of packets) to a DHCP server can eventually overflow a 32-bit reference counter, potentially causing dhcpd to crash.

Versions of DHCP affected: 4.1.0 -> 4.1-ESV-R15, 4.2.0 -> 4.2.8, 4.3.0 -> 4.3.6, 4.4.0

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.

A vulnerability stemming from failure to properly clean up closed OMAPI connections can lead to exhaustion of the pool of socket descriptors available to the DHCP server. Affects ISC DHCP 4.1.0 to 4.1-ESV-R15, 4.2.0 to 4.2.8, 4.3.0 to 4.3.6. Older versions may also be affected but are well beyond their end-of-life (EOL). Releases prior to 4.1.0 have not been tested.

A flaw was found in the Dynamic Host Configuration Protocol (DHCP). There is a discrepancy between the code that handles encapsulated option information in leases transmitted "on the wire" and the code which reads and parses lease information after it has been written to disk storage. This flaw allows an attacker to deliberately cause a situation where dhcpd while running in DHCPv4 or DHCPv6 mode, or the dhclient attempts to read a stored lease that contains option information, to trigger a stack-based buffer overflow in the option parsing code for colon-separated hex digits values. The highest threat from this vulnerability is to data confidentiality and integrity as well as service availability.

ISC DHCP 4.x before 4.1-ESV-R12-P1, 4.2.x, and 4.3.x before 4.3.3-P1 allows remote attackers to cause a denial of service (application crash) via an invalid length field in a UDP IPv4 packet.