CVE-2019-6470· NVD / CVE Program· CNA isc

dhcpd: use-after-free error leads crash in IPv6 mode when using mismatched BIND libraries

There had existed in one of the ISC BIND libraries a bug in a function that was used by dhcpd when operating in DHCPv6 mode. There was also a bug in dhcpd relating to the use of this function per its documentation, but the bug in the library function prevented this from causing any harm. All releases of dhcpd from ISC contain copies of this, and other, BIND libraries in combinations that have been tested prior to release and are known to not present issues like this. Some third-party packagers of ISC software have modified the dhcpd source, BIND source, or version matchup in ways that create the crash potential. Based on reports available to ISC, the crash probability is large and no analysis has been done on how, or even if, the probability can be manipulated by an attacker. Affects: Builds of dhcpd versions prior to version 4.4.1 when using BIND versions 9.11.2 or later, or BIND versions with specific bug fixes backported to them. ISC does not have access to comprehensive version lists for all repackagings of dhcpd that are vulnerable. In particular, builds from other vendors may also be affected. Operators are advised to consult their vendor documentation.

HighCVSS 7.5 · v3.1—No exploit Fix available

Published: Nov 1, 2019
Updated: Jun 16, 2026
EPSS: 8.8% · 95th percentile
CWE: —

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Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 3 / 30 · 8.8%

CNA vs NVD score

NVD: 7.5
CNA · isc: 6.5; 1.0 point gap

CVSS:3.1/AV:A/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.

Noroxi analysis

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Affected systems

Vendor	Product	CPE
isc	dhcpd	cpe:2.3:a:isc:dhcpd
redhat	enterprise linux	cpe:2.3:o:redhat:enterprise_linux
redhat	enterprise linux desktop	cpe:2.3:o:redhat:enterprise_linux_desktop
redhat	enterprise linux eus	cpe:2.3:o:redhat:enterprise_linux_eus
redhat	enterprise linux for arm 64	cpe:2.3:o:redhat:enterprise_linux_for_arm_64
redhat	enterprise linux for arm 64 eus	cpe:2.3:o:redhat:enterprise_linux_for_arm_64_eus
redhat	enterprise linux for ibm z systems	cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems
redhat	enterprise linux for ibm z systems eus	cpe:2.3:o:redhat:enterprise_linux_for_ibm_z_systems_eus
redhat	enterprise linux for power big endian	cpe:2.3:o:redhat:enterprise_linux_for_power_big_endian
redhat	enterprise linux for power little endian	cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian
redhat	enterprise linux for power little endian eus	cpe:2.3:o:redhat:enterprise_linux_for_power_little_endian_eus
redhat	enterprise linux for scientific computing	cpe:2.3:o:redhat:enterprise_linux_for_scientific_computing

and 7 more

Affected versions

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

isc dhcpdbefore 4.4.1
opensuse leap15.0
opensuse leap15.1
redhat enterprise linux8.0
redhat enterprise linux desktop7.0
redhat enterprise linux eus8.1
redhat enterprise linux eus8.2
redhat enterprise linux eus8.4
redhat enterprise linux eus8.6
redhat enterprise linux eus8.8
redhat enterprise linux for arm 648.0
redhat enterprise linux for arm 64 eus8.1_aarch64
redhat enterprise linux for arm 64 eus8.2_aarch64
redhat enterprise linux for arm 64 eus8.4_aarch64
redhat enterprise linux for arm 64 eus8.6_aarch64
redhat enterprise linux for arm 64 eus8.8_aarch64
redhat enterprise linux for ibm z systems7.0
redhat enterprise linux for ibm z systems8.0
redhat enterprise linux for ibm z systems eus8.1_s390x
redhat enterprise linux for ibm z systems eus8.2_s390x

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.

Multiple, non-ISC dhcpd
- builds not wholly from ISC source < 4.4.1affected

Package-level exposure

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

Ecosystem	Package	Affected range	Fix
Alpine:v3.11	dhcp	before 4.4.1-r0	4.4.1-r0
Debian:12	isc-dhcp	before 4.4.1-2	4.4.1-2
openSUSE:Leap 15.0	dhcp	before 4.3.5-lp150.5.3.1	4.3.5-lp150.5.3.1
openSUSE:Leap 15.1	dhcp	before 4.3.5-lp151.6.3.1	4.3.5-lp151.6.3.1
openSUSE:Tumbleweed	dhcp	before 4.4.2.P1-2.4	4.4.2.P1-2.4
Red Hat:enterprise_linux:7::client	dhclient	before 12:4.2.5-77.el7	12:4.2.5-77.el7
Red Hat:enterprise_linux:7::client	dhcp	before 12:4.2.5-77.el7	12:4.2.5-77.el7
Red Hat:enterprise_linux:7::client	dhcp-common	before 12:4.2.5-77.el7	12:4.2.5-77.el7
Red Hat:enterprise_linux:7::client	dhcp-debuginfo	before 12:4.2.5-77.el7	12:4.2.5-77.el7
Red Hat:enterprise_linux:7::client	dhcp-devel	before 12:4.2.5-77.el7	12:4.2.5-77.el7
Red Hat:enterprise_linux:7::client	dhcp-libs	before 12:4.2.5-77.el7	12:4.2.5-77.el7
Red Hat:enterprise_linux:8::baseos	dhcp	before 12:4.3.6-34.el8	12:4.3.6-34.el8
Red Hat:enterprise_linux:8::baseos	dhcp-client	before 12:4.3.6-34.el8	12:4.3.6-34.el8
Red Hat:enterprise_linux:8::baseos	dhcp-client-debuginfo	before 12:4.3.6-34.el8	12:4.3.6-34.el8
Red Hat:enterprise_linux:8::baseos	dhcp-common	before 12:4.3.6-34.el8	12:4.3.6-34.el8
Red Hat:enterprise_linux:8::baseos	dhcp-debuginfo	before 12:4.3.6-34.el8	12:4.3.6-34.el8
Red Hat:enterprise_linux:8::baseos	dhcp-debugsource	before 12:4.3.6-34.el8	12:4.3.6-34.el8
Red Hat:enterprise_linux:8::baseos	dhcp-libs	before 12:4.3.6-34.el8	12:4.3.6-34.el8
Red Hat:enterprise_linux:8::baseos	dhcp-libs-debuginfo	before 12:4.3.6-34.el8	12:4.3.6-34.el8
Red Hat:enterprise_linux:8::baseos	dhcp-relay	before 12:4.3.6-34.el8	12:4.3.6-34.el8
Red Hat:enterprise_linux:8::baseos	dhcp-relay-debuginfo	before 12:4.3.6-34.el8	12:4.3.6-34.el8
Red Hat:enterprise_linux:8::baseos	dhcp-server	before 12:4.3.6-34.el8	12:4.3.6-34.el8
Red Hat:enterprise_linux:8::baseos	dhcp-server-debuginfo	before 12:4.3.6-34.el8	12:4.3.6-34.el8
SUSE:Linux Enterprise Desktop 12 SP4	dhcp	before 4.3.3-10.19.1	4.3.3-10.19.1

Same product

isc: all records

Other highest-scoring records for the same primary product.

CVE-2004-0460Buffer overflow in the logging capability for the DHCP daemon (DHCPD) for ISC DHCP 3.0.1rc12 and 3.0.1rc13 allows remote attackers to cause
54Plan
CVE-2002-0702Format string vulnerabilities in the logging routines for dynamic DNS code (print.c) of ISC DHCP daemon (DHCPD) 3 to 3.0.1rc8, with the NSUP
49Plan
CVE-2004-0461The DHCP daemon (DHCPD) for ISC DHCP 3.0.1rc12 and 3.0.1rc13, when compiled in environments that do not provide the vsnprintf function, uses
45Plan
CVE-2004-1006Format string vulnerability in the log functions in dhcpd for dhcp 2.x allows remote DNS servers to execute arbitrary code via certain DNS m
42Plan
CVE-2003-0026Multiple stack-based buffer overflows in the error handling routines of the minires library, as used in the NSUPDATE capability for ISC DHCP
36Monitor
CVE-2003-0039ISC dhcrelay (dhcp-relay) 3.0rc9 and earlier, and possibly other versions, allows remote attackers to cause a denial of service (packet stor
22Monitor

Remediation

Which version to upgrade to

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

Product / package	Fixed version	Source
alpine:dhcp	4.4.1-r0 · Alpine:v3.11	Package registry (OSV)
debian:isc-dhcp	4.4.1-2 · Debian:12	Package registry (OSV)
opensuse:dhcp	4.3.5-lp150.5.3.1 · openSUSE:Leap 15.0	Package registry (OSV)
red hat:dhclient	12:4.2.5-77.el7 · Red Hat:enterprise_linux:7::client	Package registry (OSV)
red hat:dhcp	12:4.2.5-77.el7 · Red Hat:enterprise_linux:7::client	Package registry (OSV)
red hat:dhcp-client	12:4.3.6-34.el8 · Red Hat:enterprise_linux:8::baseos	Package registry (OSV)
red hat:dhcp-client-debuginfo	12:4.3.6-34.el8 · Red Hat:enterprise_linux:8::baseos	Package registry (OSV)
red hat:dhcp-common	12:4.2.5-77.el7 · Red Hat:enterprise_linux:7::client	Package registry (OSV)
red hat:dhcp-debuginfo	12:4.2.5-77.el7 · Red Hat:enterprise_linux:7::client	Package registry (OSV)
red hat:dhcp-debugsource	12:4.3.6-34.el8 · Red Hat:enterprise_linux:8::baseos	Package registry (OSV)
red hat:dhcp-devel	12:4.2.5-77.el7 · Red Hat:enterprise_linux:7::client	Package registry (OSV)
red hat:dhcp-libs	12:4.2.5-77.el7 · Red Hat:enterprise_linux:7::client	Package registry (OSV)
red hat:dhcp-libs-debuginfo	12:4.3.6-34.el8 · Red Hat:enterprise_linux:8::baseos	Package registry (OSV)
red hat:dhcp-relay	12:4.3.6-34.el8 · Red Hat:enterprise_linux:8::baseos	Package registry (OSV)
red hat:dhcp-relay-debuginfo	12:4.3.6-34.el8 · Red Hat:enterprise_linux:8::baseos	Package registry (OSV)
suse:dhcp	4.3.5-6.3.1 · SUSE:Linux Enterprise Module for Basesystem 15	Package 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.

Credits

All researchers

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

No credits in the CNA record.

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

Weakness class (CWE)

—

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

Fix✗ → ✓Sep 28, 2026, 10:47 PM UTC

For records you follow, these changes also arrive as notifications. →

References

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

All records

Noroxi analysis

No Noroxi analysis for this record yet

We use this product, ask for help

Data sources and verification

CNA: isc

CVE.org (CNA)Sep 17, 2024, 1:25 AM UTC
NVDJun 16, 2026, 10:39 PM UTC
FIRST EPSSSep 30, 2026, 12:00 AM UTC
OSV / GHSAOct 1, 2026, 3:23 AM UTC

Each line is when that source was last processed for this record.

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