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CVE-2018-5732· NVD / CVE Program· CNA isc

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

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

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Oct 9, 2019
Updated
Jun 16, 2026
EPSS
5.2% · 92th percentile
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Report tools

JSON

Action score

32

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
2 / 30 · 5.2%

CNA vs NVD score

NVD
7.5
CNA · isc
7.5
agree

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

VendorProduct
iscdhcp

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • isc dhcp4.1.0 and later · up to 4.1.2 inclusive
  • isc dhcp4.2.0 and later · before 4.2.8
  • isc dhcp4.3.0 and later · before 4.3.6
  • isc dhcp4.1-esv
  • isc dhcp4.1.2
  • isc dhcp4.4.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (isc). Independent of NVD's CPE analysis and usually ahead of it.

  • ISC ISC DHCP

    • ISC DHCP 4.1.0 -> 4.1-ESV-R15, 4.2.0 -> 4.2.8, 4.3.0 -> 4.3.6, 4.4.0affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Alpine:v3.10dhcpfrom 4.1.0 · before 4.4.1-r04.4.1-r0
Debian:12isc-dhcpbefore 4.3.5-3.14.3.5-3.1
Debian:7isc-dhcpbefore 4.2.2.dfsg.1-5+deb70u94.2.2.dfsg.1-5+deb70u9
Debian:8isc-dhcpbefore 4.3.1-6+deb8u34.3.1-6+deb8u3
Debian:9isc-dhcpbefore 4.3.5-3+deb9u14.3.5-3+deb9u1
openSUSE:Tumbleweeddhcpbefore 4.4.2.P1-2.44.4.2.P1-2.4
Red Hat:enterprise_linux:6::clientdhclientbefore 12:4.1.1-53.P1.el6_9.312:4.1.1-53.P1.el6_9.3
Red Hat:enterprise_linux:6::clientdhcpbefore 12:4.1.1-53.P1.el6_9.312:4.1.1-53.P1.el6_9.3
Red Hat:enterprise_linux:6::clientdhcp-commonbefore 12:4.1.1-53.P1.el6_9.312:4.1.1-53.P1.el6_9.3
Red Hat:enterprise_linux:6::clientdhcp-debuginfobefore 12:4.1.1-53.P1.el6_9.312:4.1.1-53.P1.el6_9.3
Red Hat:enterprise_linux:6::clientdhcp-develbefore 12:4.1.1-53.P1.el6_9.312:4.1.1-53.P1.el6_9.3
Red Hat:enterprise_linux:7::clientdhclientbefore 12:4.2.5-58.el7_4.312:4.2.5-58.el7_4.3
Red Hat:enterprise_linux:7::clientdhcpbefore 12:4.2.5-58.el7_4.312:4.2.5-58.el7_4.3
Red Hat:enterprise_linux:7::clientdhcp-commonbefore 12:4.2.5-58.el7_4.312:4.2.5-58.el7_4.3
Red Hat:enterprise_linux:7::clientdhcp-debuginfobefore 12:4.2.5-58.el7_4.312:4.2.5-58.el7_4.3
Red Hat:enterprise_linux:7::clientdhcp-develbefore 12:4.2.5-58.el7_4.312:4.2.5-58.el7_4.3
Red Hat:enterprise_linux:7::clientdhcp-libsbefore 12:4.2.5-58.el7_4.312:4.2.5-58.el7_4.3
SUSE:Linux Enterprise Desktop 12 SP2dhcpbefore 4.3.3-10.14.14.3.3-10.14.1
SUSE:Linux Enterprise Software Development Kit 11 SP4dhcpbefore 4.2.4.P2-0.28.8.14.2.4.P2-0.28.8.1

Same product

isc: all records

Other highest-scoring records for the same primary product.

  • CVE-2011-0997dhclient 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 t
    55Plan
  • CVE-2017-3144Failure to properly clean up closed OMAPI connections can exhaust available sockets
    52Plan
  • CVE-2015-8605ISC 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
    51Plan
  • CVE-2009-0692Stack-based buffer overflow in the script_write_params method in client/dhclient.c in ISC DHCP dhclient 4.1 before 4.1.0p1, 4.0 before 4.0.1
    48Plan
  • CVE-2016-2774ISC 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 rem
    45Plan
  • CVE-2011-2749The 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
    43Plan

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
alpine:dhcp4.4.1-r0 · Alpine:v3.10Package registry (OSV)
debian:isc-dhcp4.3.5-3.1 · Debian:12Package registry (OSV)
opensuse:dhcp4.4.2.P1-2.4 · openSUSE:TumbleweedPackage registry (OSV)
red hat:dhclient12:4.1.1-53.P1.el6_9.3 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
red hat:dhcp12:4.1.1-53.P1.el6_9.3 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
red hat:dhcp-common12:4.1.1-53.P1.el6_9.3 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
red hat:dhcp-debuginfo12:4.1.1-53.P1.el6_9.3 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
red hat:dhcp-devel12:4.1.1-53.P1.el6_9.3 · Red Hat:enterprise_linux:6::clientPackage registry (OSV)
red hat:dhcp-libs12:4.2.5-58.el7_4.3 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
suse:dhcp4.2.4.P2-0.28.8.1 · SUSE:Linux Enterprise Software Development Kit 11 SP4Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Noroxi analysis

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Change log

  1. Fix✗ → ✓

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References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records