FreeBSD < 10.3-RELEASE-p21 / 11.0 < 11.0-RELEASE-p12 / 11.1 < 11.1-RELEASE-p1 OpenSSH Password Length DoS (FreeBSD-SA-17:06.openssh)

High Nessus Plugin ID 102917


The remote FreeBSD host is missing a security-related update.


The version of the FreeBSD kernel running on the remote host is prior to 10.3-RELEASE-p21, 11.0 prior to 11.0-RELEASE-p12, or 11.1 prior to 11.1-RELEASE-p1. It, therefore, affected by a flaw in built-in password authentication in OpenSSH. An unauthenticated, remote attacker can exploit this issue by sending very long passwords when PasswordAuthentication is enabled by the system administrator, resulting in a denial of service condition.

Note that this issue only affects hosts with PasswordAuthentication enabled in /etc/ssh/sshd_config (the default FreeBSD configuration).

You may workaround this issue by disabling PasswordAuthentication and restarting sshd.


Upgrade to FreeBSD version 10.3-RELEASE-p21 / 11.0-RELEASE-p12 / 11.1-RELEASE-p1 or later. Alternatively, apply the workaround referenced in the advisory to disable PasswordAuthentication.

See Also

Plugin Details

Severity: High

ID: 102917

File Name: freebsd_sa-17-06_openssh.nasl

Version: $Revision: 1.2 $

Type: local

Published: 2017/09/01

Modified: 2017/11/30

Dependencies: 12634

Risk Information

Risk Factor: High


Base Score: 7.8

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:C


Base Score: 7.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vulnerability Information

CPE: cpe:/o:freebsd:freebsd

Required KB Items: Host/local_checks_enabled, Host/FreeBSD/release, Host/FreeBSD/pkg_info, Settings/ParanoidReport

Patch Publication Date: 2017/08/10

Vulnerability Publication Date: 2017/08/10

Reference Information

CVE: CVE-2016-6515

BID: 92212