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Vulnerability record · CVE-2016-8858 · published 9 December 2016

CVE-2016-8858: Openbsd openssh uncontrolled resource consumption vulnerability

Openbsd · Openssh

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."

7.5 CVSS 3.1 High EPSS 29% · top 1.9% CWE-399 · CWE-399CWE-400 · Uncontrolled resource consumption
7.5CVSS 3.1 base score, v2 7.8
29%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
26References
17 Jun 2026Last modified by NVD

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."

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c.diff?r1=1.126&r2=1.127&f=h Issue TrackingVendor Advisory
http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c?rev=1.127&content-type=text/x-cvsweb-markup Issue TrackingVendor Advisory
http://www.openwall.com/lists/oss-security/2016/10/19/3 Mailing ListThird Party Advisory
http://www.openwall.com/lists/oss-security/2016/10/20/1 Mailing ListThird Party Advisory
http://www.securityfocus.com/bid/93776 Third Party AdvisoryVDB Entry
http://www.securitytracker.com/id/1037057 Third Party AdvisoryVDB Entry
https://bugzilla.redhat.com/show_bug.cgi?id=1384860 Issue Tracking
https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
https://ftp.openbsd.org/pub/OpenBSD/patches/6.0/common/013_ssh_kexinit.patch.sig PatchVendor Advisory
https://github.com/openssh/openssh-portable/commit/ec165c392ca54317dbe3064a8c200de6531e89ad Issue TrackingPatchThird Party Advisory
https://security.FreeBSD.org/advisories/FreeBSD-SA-16:33.openssh.asc Third Party Advisory
https://security.gentoo.org/glsa/201612-18 Third Party Advisory
https://security.netapp.com/advisory/ntap-20180201-0001/ Third Party Advisory
http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c.diff?r1=1.126&r2=1.127&f=h Issue TrackingVendor Advisory
http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c?rev=1.127&content-type=text/x-cvsweb-markup Issue TrackingVendor Advisory
http://www.openwall.com/lists/oss-security/2016/10/19/3 Mailing ListThird Party Advisory
http://www.openwall.com/lists/oss-security/2016/10/20/1 Mailing ListThird Party Advisory
http://www.securityfocus.com/bid/93776 Third Party AdvisoryVDB Entry
http://www.securitytracker.com/id/1037057 Third Party AdvisoryVDB Entry
https://bugzilla.redhat.com/show_bug.cgi?id=1384860 Issue Tracking
https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
https://ftp.openbsd.org/pub/OpenBSD/patches/6.0/common/013_ssh_kexinit.patch.sig PatchVendor Advisory
https://github.com/openssh/openssh-portable/commit/ec165c392ca54317dbe3064a8c200de6531e89ad Issue TrackingPatchThird Party Advisory
https://security.FreeBSD.org/advisories/FreeBSD-SA-16:33.openssh.asc Third Party Advisory
https://security.gentoo.org/glsa/201612-18 Third Party Advisory
https://security.netapp.com/advisory/ntap-20180201-0001/ Third Party Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2016-8858), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.