---
title: "CVE-2016-8858\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-2016-8858?format=md
keywords: index, follow
---

# CVE-2016-8858

Publication date 9 December 2016

Last updated 4 August 2025

---

Ubuntu priority

**Negligible**

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

## Cvss 3 Severity Score

**7.5 · High**

[Score breakdown](https://ubuntu.com/security/CVE-2016-8858?format=md#impact-score)

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## Description

The kex\_input\_kexinit function in kex.c in OpenSSH 6.x and 7.x through 7.3
allows remote attackers to cause a denial of service (memory consumption)
by sending many duplicate KEXINIT requests. NOTE: a third party reports
that "OpenSSH upstream does not consider this as a security issue."

[Read the notes from the security team](https://ubuntu.com/security/CVE-2016-8858?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| openssh | 17.10 artful | Not affected |
| 17.04 zesty | Not affected |
| 16.10 yakkety | Ignored end of life |
| 16.04 LTS xenial | Ignored |
| 14.04 LTS trusty | Ignored |
| 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-2016-8858?format=md#patch-details)

## Notes

---

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

DoS is limited to attacker's connection only, and openssh
upstream does not consider this to be a security issue
We do not consider this to be a security issue either, marking
as ignored

### 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 |
| --- | --- |
| openssh | * Upstream:   [ec165c3](https://github.com/openssh/openssh-portable/commit/ec165c392ca54317dbe3064a8c200de6531e89ad) |

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

7.5 · High

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 7.5 · High |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2016-8858)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2016-8858)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2016-8858)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2016-8858)

### Other references

* <http://seclists.org/oss-sec/2016/q4/185>
* <https://www.cve.org/CVERecord?id=CVE-2016-8858>