CVE-2016-8858

Publication date 9 December 2016

Last updated 4 August 2025

Ubuntu priority

Cvss 3 Severity Score

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

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

Notes

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?

Package	Patch details
openssh	Upstream: ec165c3

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