title: A specially constructed response from a malicious server can cause a buffer overflow in dhclient
description: Failure to properly bounds-check a buffer used for processing DHCP options allows a malicious server (or an entity masquerading as a server) to cause a buffer overflow (and resulting crash) in dhclient by sending a response containing a specially constructed options section. Affects ISC DHCP versions 4.1.0 -> 4.1-ESV-R15, 4.2.0 -> 4.2.8, 4.3.0 -> 4.3.6, 4.4.0
problem types: Affected versions of dhclient should crash due to an out-of-bounds memory access if they receive and process a triggering response packet. However, buffer overflow outcomes can vary by operating system, and outcomes such as remote code execution may be possible in some circumstances. Where they are present, operating system mitigation strategies such as address space layout randomization (ASLR) should make it difficult to leverage this vulnerability to achieve remote code execution, but we cannot rule it out as impossible. The safest course is to patch dhclient so that the buffer overflow cannot occur.
affected:
{
product: ISC DHCP
vendor: ISC
versions:
status: affected, version: ISC DHCP 4.1.0 -> 4.1-ESV-R15, 4.2.0 -> 4.2.8, 4.3.0 -> 4.3.6, 4.4.0
}
metrics:
cvssV3_0: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: HIGH
baseScore: 7.5
baseSeverity: HIGH
confidentialityImpact: NONE
integrityImpact: NONE
privilegesRequired: NONE
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
version: 3.0
]
solutions: Upgrade to the patched release most closely related to your current version of DHCP. ISC DHCP releases are available from https://www.isc.org/downloads.
>=   DHCP 4.1-ESV-R15-P1
>=   DHCP 4.3.6-P1
>=   DHCP 4.4.1