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
- Published
- Oct 9, 2019
- Updated
- Jun 16, 2026
- EPSS
- 5.2% · 92th percentile
- CWE
- CWE-119
Sign in to follow · You’ll be notified if a followed record enters KEV, gets an exploit or is updated.
Report tools
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
| Vendor | Product | CPE |
|---|---|---|
| isc | dhcp | cpe:2.3:a:isc:dhcp |
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.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.10 | dhcp | from 4.1.0 · before 4.4.1-r0 | 4.4.1-r0 |
| Debian:12 | isc-dhcp | before 4.3.5-3.1 | 4.3.5-3.1 |
| Debian:7 | isc-dhcp | before 4.2.2.dfsg.1-5+deb70u9 | 4.2.2.dfsg.1-5+deb70u9 |
| Debian:8 | isc-dhcp | before 4.3.1-6+deb8u3 | 4.3.1-6+deb8u3 |
| Debian:9 | isc-dhcp | before 4.3.5-3+deb9u1 | 4.3.5-3+deb9u1 |
| openSUSE:Tumbleweed | dhcp | before 4.4.2.P1-2.4 | 4.4.2.P1-2.4 |
| Red Hat:enterprise_linux:6::client | dhclient | before 12:4.1.1-53.P1.el6_9.3 | 12:4.1.1-53.P1.el6_9.3 |
| Red Hat:enterprise_linux:6::client | dhcp | before 12:4.1.1-53.P1.el6_9.3 | 12:4.1.1-53.P1.el6_9.3 |
| Red Hat:enterprise_linux:6::client | dhcp-common | before 12:4.1.1-53.P1.el6_9.3 | 12:4.1.1-53.P1.el6_9.3 |
| Red Hat:enterprise_linux:6::client | dhcp-debuginfo | before 12:4.1.1-53.P1.el6_9.3 | 12:4.1.1-53.P1.el6_9.3 |
| Red Hat:enterprise_linux:6::client | dhcp-devel | before 12:4.1.1-53.P1.el6_9.3 | 12:4.1.1-53.P1.el6_9.3 |
| Red Hat:enterprise_linux:7::client | dhclient | before 12:4.2.5-58.el7_4.3 | 12:4.2.5-58.el7_4.3 |
| Red Hat:enterprise_linux:7::client | dhcp | before 12:4.2.5-58.el7_4.3 | 12:4.2.5-58.el7_4.3 |
| Red Hat:enterprise_linux:7::client | dhcp-common | before 12:4.2.5-58.el7_4.3 | 12:4.2.5-58.el7_4.3 |
| Red Hat:enterprise_linux:7::client | dhcp-debuginfo | before 12:4.2.5-58.el7_4.3 | 12:4.2.5-58.el7_4.3 |
| Red Hat:enterprise_linux:7::client | dhcp-devel | before 12:4.2.5-58.el7_4.3 | 12:4.2.5-58.el7_4.3 |
| Red Hat:enterprise_linux:7::client | dhcp-libs | before 12:4.2.5-58.el7_4.3 | 12:4.2.5-58.el7_4.3 |
| SUSE:Linux Enterprise Desktop 12 SP2 | dhcp | before 4.3.3-10.14.1 | 4.3.3-10.14.1 |
| SUSE:Linux Enterprise Software Development Kit 11 SP4 | dhcp | before 4.2.4.P2-0.28.8.1 | 4.2.4.P2-0.28.8.1 |
Same product
isc: all recordsOther 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 t55Plan
- CVE-2017-3144Failure to properly clean up closed OMAPI connections can exhaust available sockets52Plan
- 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 crash51Plan
- 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 4.0.148Plan
- 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 rem45Plan
- 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 a43Plan
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:v3.10 | Package registry (OSV) |
| debian:isc-dhcp | 4.3.5-3.1 · Debian:12 | Package registry (OSV) |
| opensuse:dhcp | 4.4.2.P1-2.4 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:dhclient | 12:4.1.1-53.P1.el6_9.3 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:dhcp | 12:4.1.1-53.P1.el6_9.3 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:dhcp-common | 12:4.1.1-53.P1.el6_9.3 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:dhcp-debuginfo | 12:4.1.1-53.P1.el6_9.3 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:dhcp-devel | 12:4.1.1-53.P1.el6_9.3 · Red Hat:enterprise_linux:6::client | Package registry (OSV) |
| red hat:dhcp-libs | 12:4.2.5-58.el7_4.3 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| suse:dhcp | 4.2.4.P2-0.28.8.1 · SUSE:Linux Enterprise Software Development Kit 11 SP4 | 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.
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 researchersFinders, 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
Weakness class (CWE)
CWE-119 · Improper Restriction of Operations within the Bounds of a Memory BufferCVSS 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.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Overflow BuffersCAPEC-100likelihood: High · Very High
- Buffer ManipulationCAPEC-123likelihood: High · Very High
- Client-side Injection-induced Buffer OverflowCAPEC-14likelihood: Medium · High
- Filter Failure through Buffer OverflowCAPEC-24likelihood: High · High
- MIME ConversionCAPEC-42likelihood: High · High
- Overflow Binary Resource FileCAPEC-44likelihood: High · Very High
- Buffer Overflow via Symbolic LinksCAPEC-45likelihood: High · High
ATT&CK techniques
—
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.