CVE-2016-8858

What it is

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."

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of service disruption.

Exploit odds

29.5% chance of exploitation in the next 30 days (EPSS). Higher than most.

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2016-12-09 11:59 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 00:55 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 29.5% in the next 30 days (EPSS).
• Severity: 7.5 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2016-12-09 11:59 UTC

Last modified

2026-06-17 00:55 UTC

Exploit probability

29.5% · EPSS, next 30 days

Weakness

CWE-399

Record status

Modified

Affected

• Openbsd OpenSSH 6.8
• Openbsd OpenSSH 6.9
• Openbsd OpenSSH 7.0
• Openbsd OpenSSH 7.1
• Openbsd OpenSSH 7.2
• Openbsd OpenSSH 7.3

Attack profile CVSS 3.1 · 7.5

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2016-8858.md and follow it. Check whether this project is affected by CVE-2016-8858. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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