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NVD / CVE Program· CNA mitre

CVE-2016-2774: ISC 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…

MediumCVSS 5.9 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Plan (action score 45/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 73.6% (FIRST EPSS); higher than 99.4% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: isc-dhcp (Debian:12) 4.3.4-1; isc-dhcp (Debian:8) 4.3.1-6+deb8u4; dhclient (Red Hat:enterprise_linux:7::client) 12:4.2.5-47.el7.

Add it to your regular patch cycle. Upgrade to isc-dhcp (Debian:12) 4.3.4-1; isc-dhcp (Debian:8) 4.3.1-6+deb8u4; dhclient (Red Hat:enterprise_linux:7::client) 12:4.2.5-47.el7 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

ISC 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 remote attackers to cause a denial of service (INSIST assertion failure or request-processing outage) by establishing many sessions.

Published
Mar 9, 2016
Updated
Jun 16, 2026
EPSS
73.6% · 99th percentile

Report tools

JSON

Action score

45

Plan

Add it to your regular patch cycle.

CVSS
23 / 40 · 5.9 / 10
CISA KEV
0 / 30 · Not listed
EPSS
22 / 30 · 73.6%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
iscdhcp
debiandebian linux
canonicalubuntu linux

Affected versions

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

  • canonical ubuntu linux14.04
  • canonical ubuntu linux16.04
  • canonical ubuntu linux17.10
  • debian debian linux8.0
  • isc dhcp4.1-esv
  • isc dhcp4.1.0
  • isc dhcp4.1.1
  • isc dhcp4.1.2
+12 more rows
  • isc dhcp4.2.0
  • isc dhcp4.2.1
  • isc dhcp4.2.2
  • isc dhcp4.2.3
  • isc dhcp4.2.4
  • isc dhcp4.2.5
  • isc dhcp4.2.6
  • isc dhcp4.2.7
  • isc dhcp4.2.8
  • isc dhcp4.3.0
  • isc dhcp4.3.1
  • isc dhcp4.3.2

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12isc-dhcpbefore 4.3.4-14.3.4-1
Debian:8isc-dhcpbefore 4.3.1-6+deb8u44.3.1-6+deb8u4
Red Hat:enterprise_linux:7::clientdhclientbefore 12:4.2.5-47.el712:4.2.5-47.el7
Red Hat:enterprise_linux:7::clientdhcpbefore 12:4.2.5-47.el712:4.2.5-47.el7
Red Hat:enterprise_linux:7::clientdhcp-commonbefore 12:4.2.5-47.el712:4.2.5-47.el7
Red Hat:enterprise_linux:7::clientdhcp-debuginfobefore 12:4.2.5-47.el712:4.2.5-47.el7
Red Hat:enterprise_linux:7::clientdhcp-develbefore 12:4.2.5-47.el712:4.2.5-47.el7
Red Hat:enterprise_linux:7::clientdhcp-libsbefore 12:4.2.5-47.el712:4.2.5-47.el7
SUSE:Linux Enterprise Desktop 12dhcpbefore 4.2.6-14.6.14.2.6-14.6.1
SUSE:Linux Enterprise Desktop 12 SP1dhcpbefore 4.3.3-9.14.3.3-9.1
SUSE:Linux Enterprise Server 11 SP2-LTSSdhcpbefore 4.2.4.P2-0.11.15.14.2.4.P2-0.11.15.1
SUSE:Linux Enterprise Software Development Kit 11 SP4dhcpbefore 4.2.4.P2-0.27.14.2.4.P2-0.27.1

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…
    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…
    51Plan

Published before and after this one in the same product

  • ← EarlierCVE-2012-3955Sep 14, 2012 · ISC DHCP 4.1.x before 4.1-ESV-R7 and 4.2.x before 4.2.4-P2 allows remote attackers to cause a denial of service (daemon crash) in…
    34Monitor
  • ← EarlierCVE-2013-2494Mar 28, 2013 · libdns in ISC DHCP 4.2.x before 4.2.5-P1 allows remote name servers to cause a denial of service (memory consumption) via vectors involving…
    19Monitor
  • Later →CVE-2018-5733Jan 16, 2019 · A malicious client can overflow a reference counter in ISC dhcpd
    36Monitor

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
debian:isc-dhcp4.3.4-1 · Debian:12Package registry (OSV)
red hat:dhclient12:4.2.5-47.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:dhcp12:4.2.5-47.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:dhcp-common12:4.2.5-47.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:dhcp-debuginfo12:4.2.5-47.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:dhcp-devel12:4.2.5-47.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
red hat:dhcp-libs12:4.2.5-47.el7 · Red Hat:enterprise_linux:7::clientPackage registry (OSV)
suse:dhcp4.2.6-14.6.1 · SUSE:Linux Enterprise Desktop 12Package 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.

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

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.
  • Special conditions such as timing or configuration are required.

If successful

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

Weakness class (CWE)

CWE-20 · Improper Input Validation

CVSS vector

CVSS:3.1/AV:N/AC:H/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.

References

Show all references (9 more)

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

All records