CVE-2018-5732 — A specially constructed response from a malicious server can cause a buffer overflow in dhclient

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HIGH

A specially constructed response from a malicious server can cause a buffer overflow in dhclient

Published Oct 9, 2019

7.5

HIGH

CVSS 3.1

EPSS 5.24%

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

Affected products

Vendor ISC Product Isc Dhcp Default
n/a
- 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
  Status
  affected
  Constraints
  -

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor

Product

Default status

Versions

ISC

Isc Dhcp

n/a

Version	Status	Constraints
ISC DHCP 4.1.0 -> 4.1-ESV-R15, 4.2.0 -> 4.2.8, 4.3.0 -> 4.3.6, 4.4.0	affected	-

Red Hat Enterprise Linux 6

dhcp-12:4.1.1-53.P1.el6_9.3

Fixed · RHSA-2018:0469
Red Hat Enterprise Linux 7

dhcp-12:4.2.5-58.el7_4.3

Fixed · RHSA-2018:0483
Red Hat Enterprise Linux 5

dhcp

Will not fix
Red Hat Enterprise Linux 8

dhcp

Not affected

Product	Package	State	Advisory
Red Hat Enterprise Linux 6	dhcp-12:4.1.1-53.P1.el6_9.3	Fixed	RHSA-2018:0469
Red Hat Enterprise Linux 7	dhcp-12:4.2.5-58.el7_4.3	Fixed	RHSA-2018:0483
Red Hat Enterprise Linux 5	dhcp	Will not fix	n/a
Red Hat Enterprise Linux 8	dhcp	Not affected	n/a

Remediation

Vendor solution

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

Metrics

5.24% 0.05244

Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.

EPSS probability 0.05244

Score over time

2021–2026

EPSS v1
EPSS v2
EPSS v3
EPSS v4
EPSS v5

Percentile over time

EPSS v1
EPSS v2
EPSS v3
EPSS v4
EPSS v5

Table of values (18 key points)

Flat stretches are collapsed; showing up to 120 newest points.

Date	Score	Percentile	Model
Oct 1, 2026	5.24% (0.05244)	92.27th	v5 (v2026.06.15)
Jun 15, 2026	4.96% (0.04960)	91.04th	v5 (v2026.06.15)
May 9, 2026	2.52% (0.02521)	85.53th	v4 (v2025.03.14)
Apr 13, 2026	3.64% (0.03639)	87.85th	v4 (v2025.03.14)
Aug 1, 2025	2.37% (0.02367)	84.40th	v4 (v2025.03.14)
Jun 1, 2025	4.17% (0.04167)	88.17th	v4 (v2025.03.14)
Mar 29, 2025	2.16% (0.02158)	73.77th	v4 (v2025.03.14)
Jul 20, 2024	0.16% (0.00160)	53.06th	v3 (v2023.03.01)
May 21, 2024	0.16% (0.00160)	52.50th	v3 (v2023.03.01)
Mar 7, 2023	0.16% (0.00158)	50.49th	v3 (v2023.03.01)
Mar 6, 2023	0.89% (0.00885)	27.89th	v2 (v2022.01.01)
Sep 10, 2022	0.89% (0.00885)	26.24th	v2 (v2022.01.01)
Apr 1, 2022	0.89% (0.00885)	24.24th	v2 (v2022.01.01)
Feb 4, 2022	0.89% (0.00885)	10.50th	v2 (v2022.01.01)
Feb 3, 2022	0.42% (0.00416)	10.04th	v1
Jan 6, 2022	0.42% (0.00416)	9.79th	v1
Sep 1, 2021	0.42% (0.00416)	25.53th	v1
Apr 14, 2021	0.42% (0.00416)	0.00th	v1

Weaknesses (1)

CWE-119

Buffer Overflow

References (6)

https://access.redhat.com/security/cve/CVE-2018-5732
Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1549960
Issue Tracking
https://kb.isc.org/article/AA-01565
https://kb.isc.org/docs/aa-01565
x_refsource_CONFIRMVendor Advisory
https://nvd.nist.gov/vuln/detail/CVE-2018-5732
https://www.cve.org/CVERecord?id=CVE-2018-5732

Link	Providers	Tags
https://access.redhat.com/security/cve/CVE-2018-5732		Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1549960		Issue Tracking
https://kb.isc.org/article/AA-01565
https://kb.isc.org/docs/aa-01565		x_refsource_CONFIRMVendor Advisory
https://nvd.nist.gov/vuln/detail/CVE-2018-5732
https://www.cve.org/CVERecord?id=CVE-2018-5732