HIGH
** DISPUTED ** 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."
http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/kex.c.diff?r1=1.126&r2=1.127&f=h
http://www.openwall.com/lists/oss-security/2016/10/19/3
http://www.openwall.com/lists/oss-security/2016/10/20/1
http://www.securityfocus.com/bid/93776
http://www.securitytracker.com/id/1037057
https://bugzilla.redhat.com/show_bug.cgi?id=1384860
https://ftp.openbsd.org/pub/OpenBSD/patches/6.0/common/013_ssh_kexinit.patch.sig
https://github.com/dag-erling/kexkill/issues/1
https://github.com/openssh/openssh-portable/commit/ec165c392ca54317dbe3064a8c200de6531e89ad
https://security.FreeBSD.org/advisories/FreeBSD-SA-16:33.openssh.asc
Source: MITRE
Published: 2016-12-09
Updated: 2018-09-19
Type: CWE-399
Base Score: 7.8
Vector: (AV:N/AC:L/Au:N/C:N/I:N/A:C)
Impact Score: 6.9
Exploitability Score: 10
Severity: HIGH
Base Score: 7.5
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Impact Score: 3.6
Exploitability Score: 3.9
Severity: HIGH