Your submission was sent successfully! Close

You have successfully unsubscribed! Close

Thank you for signing up for our newsletter!
In these regular emails you will find the latest updates about Ubuntu and upcoming events where you can meet our team.Close

CVE-2021-25217

Published: 26 May 2021

In ISC DHCP 4.1-ESV-R1 -> 4.1-ESV-R16, ISC DHCP 4.4.0 -> 4.4.2 (Other branches of ISC DHCP (i.e., releases in the 4.0.x series or lower and releases in the 4.3.x series) are beyond their End-of-Life (EOL) and no longer supported by ISC. From inspection it is clear that the defect is also present in releases from those series, but they have not been officially tested for the vulnerability), The outcome of encountering the defect while reading a lease that will trigger it varies, according to: the component being affected (i.e., dhclient or dhcpd) whether the package was built as a 32-bit or 64-bit binary whether the compiler flag -fstack-protection-strong was used when compiling In dhclient, ISC has not successfully reproduced the error on a 64-bit system. However, on a 32-bit system it is possible to cause dhclient to crash when reading an improper lease, which could cause network connectivity problems for an affected system due to the absence of a running DHCP client process. In dhcpd, when run in DHCPv4 or DHCPv6 mode: if the dhcpd server binary was built for a 32-bit architecture AND the -fstack-protection-strong flag was specified to the compiler, dhcpd may exit while parsing a lease file containing an objectionable lease, resulting in lack of service to clients. Additionally, the offending lease and the lease immediately following it in the lease database may be improperly deleted. if the dhcpd server binary was built for a 64-bit architecture OR if the -fstack-protection-strong compiler flag was NOT specified, the crash will not occur, but it is possible for the offending lease and the lease which immediately followed it to be improperly deleted.

Priority

Medium

Cvss 3 Severity Score

7.4

Score breakdown

Status

Package Release Status
isc-dhcp
Launchpad, Ubuntu, Debian
impish
Released (4.4.1-2.2ubuntu7)
jammy
Released (4.4.1-2.2ubuntu7)
upstream Needs triage

xenial
Released (4.3.3-5ubuntu12.10+esm1)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only)
bionic
Released (4.3.5-3ubuntu7.3)
focal
Released (4.4.1-2.1ubuntu5.20.04.2)
groovy
Released (4.4.1-2.1ubuntu10.1)
hirsute
Released (4.4.1-2.2ubuntu6.1)
trusty
Released (4.2.4-7ubuntu12.13+esm1)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only)
Patches:
upstream: https://downloads.isc.org/isc/dhcp/private/faaa35f1cb9dc2e8 (4.1-ESV-R16-P1)
upstream: https://downloads.isc.org/isc/dhcp/private/3089a1ebd20a802e (4.4.2-P1)

Severity score breakdown

Parameter Value
Base score 7.4
Attack vector Adjacent
Attack complexity Low
Privileges required None
User interaction None
Scope Changed
Confidentiality None
Integrity impact None
Availability impact High
Vector CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H