---
title: "CVE-2016-2774\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/security/CVE-2016-2774?format=md
keywords: index, follow
---

# CVE-2016-2774

Publication date 9 March 2016

Last updated 25 August 2025

---

Ubuntu priority

**Low**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**5.9 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2016-2774?format=md#impact-score)

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## Description

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.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2016-2774?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| isc-dhcp | 21.04 hirsute | Not affected |
| 20.10 groovy | Not affected |
| 20.04 LTS focal | Not affected |
| 19.10 eoan | Not affected |
| 19.04 disco | Not affected |
| 18.10 cosmic | Not affected |
| 18.04 LTS bionic | Not affected |
| 17.10 artful | Not affected |
| 17.04 zesty | Ignored end of life |
| 16.10 yakkety | Ignored end of life |
| 16.04 LTS xenial | Fixed 4.3.3-5ubuntu12.9 |
| 15.10 wily | Ignored end of life |
| 14.04 LTS trusty | Fixed 4.2.4-7ubuntu12.12 |
| 12.04 LTS precise | Ignored end of life |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)
* [Patch details](https://ubuntu.com/security/CVE-2016-2774?format=md#patch-details)

## Notes

---

### [mdeslaur](https://launchpad.net/~mdeslaur)

DoS over OMAPI and failover ports only, see ISC kb article
for workarounds, or properly limit access to ports

### Patch details

For informational purposes only. We recommend not to cherry-pick updates. [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)

| Package | Patch details |
| --- | --- |
| isc-dhcp | * Upstream:   <https://source.isc.org/cgi-bin/gitweb.cgi?p=dhcp.git;a=commit;h=0b209ea5cc333255e055113fa2ad636dda681a21> |

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

5.9 · Medium

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Network |
  | Attack complexity | High |
  | Privileges required | None |
  | User interaction | None |
  | Scope | Unchanged |
  | Confidentiality impact | None |
  | Integrity impact | None |
  | Availability impact | High |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 5.9 · Medium |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-2774)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2016-2774)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2016-2774)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2016-2774)

### Related Ubuntu Security Notices (USN)

+ [USN-3586-1](https://usn.ubuntu.com/USN-3586-1)
+ DHCP vulnerabilities
+ 1 March 2018

### Other references

* <https://kb.isc.org/article/AA-01354>
* <https://www.cve.org/CVERecord?id=CVE-2016-2774>