Public proof of conceptFix available

CVE-2016-8858

A public proof of concept exists; no exploitation attested.

Published2016-12-09
WeaknessCWE-399 · CWE-400

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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."

Timeline

dates in UTC

2016-12-0911:59CVE publishedNVD
2026-10-2319:23First public proof of conceptPoC-in-GitHub
2026-10-2319:23EPSS crossed 10 %FIRST EPSS

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2016-8858?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2016-8858?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

OpenSSH

Branch	Affected	Fixed in	Source
6.8	= 6.8	no fix published	NVD
6.9	= 6.9	no fix published	NVD
7.0	= 7.0	no fix published	NVD
7.1	= 7.1	no fix published	NVD
7.2	= 7.2	no fix published	NVD
7.3	= 7.3	no fix published	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Advisories and patches

cvsweb.openbsd.orgVendor Advisory
cvsweb.openbsd.orgVendor Advisory
ftp.openbsd.orgPatch · Vendor Advisory
github.comPatch

Detection

read 2026-10-23 19:23 UTC

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: 1 repository, unverifieddag-erling/kexkill

Sources

CISA-ADPSSVC decisionnone2024-04-15
OpenCVESSVC decisionnone—
CISA-ADPCVSS 3.17.52026-05-29
NVDCVSS 3.07.5read 2026-10-23
NVDCVSS 2.07.8read 2026-10-23
CISA-ADPweakness (CWE)CWE-4002026-05-29
NVDweakness (CWE)CWE-399read 2026-10-23
FIRST EPSSEPSS score29.5 %read 2026-10-23
PoC-in-GitHubproof of concept1read 2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published: 2016-12-09
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2016-8858?

Is CVE-2016-8858 actively exploited?

Active exploitation of CVE-2016-8858 has not been confirmed. Its EPSS score was 29.5% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2016-8858?

CVE-2016-8858 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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