Cisco NX-OS Software Network Time Protocol Denial of Service (CVE-2019-1967)

high Tenable OT Security Plugin ID 501255


The remote OT asset is affected by a vulnerability.


A vulnerability in the Network Time Protocol (NTP) feature of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to excessive use of system resources when the affected device is logging a drop action for received MODE_PRIVATE (Mode 7) NTP packets. An attacker could exploit this vulnerability by flooding the device with a steady stream of Mode 7 NTP packets. A successful exploit could allow the attacker to cause high CPU and memory usage on the affected device, which could cause internal system processes to restart or cause the affected device to unexpectedly reload. Note: The NTP feature is enabled by default.

This plugin only works with Tenable.ot.
Please visit for more information.


Refer to the vendor advisory.

See Also

Plugin Details

Severity: High

ID: 501255

Version: 1.1

Type: remote

Family: Tenable.ot

Published: 7/25/2023

Updated: 7/26/2023

Supported Sensors: Nessus

Risk Information


Risk Factor: Low

Score: 3.6


Risk Factor: High

Base Score: 7.8

Temporal Score: 5.8

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

CVSS Score Source: CVE-2019-1967


Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

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

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:cisco:nx-os:6.0%282%29a8, cpe:/o:cisco:nx-os:6.0%282%29a8%289.7%29, cpe:/o:cisco:nx-os:6.0%282%29u6, cpe:/o:cisco:nx-os:6.2, cpe:/o:cisco:nx-os:7.0%283%29f, cpe:/o:cisco:nx-os:7.0%283%29i, cpe:/o:cisco:nx-os:7.0%283%29i7, cpe:/o:cisco:nx-os:7.1%284%29, cpe:/o:cisco:nx-os:7.1%284%29n1%281%29, cpe:/o:cisco:nx-os:7.1%285%29, cpe:/o:cisco:nx-os:7.2, cpe:/o:cisco:nx-os:7.3, cpe:/o:cisco:nx-os:7.3%282%29d1%281%29, cpe:/o:cisco:nx-os:8.0, cpe:/o:cisco:nx-os:8.1, cpe:/o:cisco:nx-os:8.2, cpe:/o:cisco:nx-os:8.3, cpe:/o:cisco:nx-os:8.3%282%29s5, cpe:/o:cisco:nx-os:9.2, cpe:/o:cisco:nx-os:9.2%281%29

Required KB Items: Tenable.ot/Cisco

Exploit Ease: No known exploits are available

Patch Publication Date: 8/30/2019

Vulnerability Publication Date: 8/30/2019

Reference Information

CVE: CVE-2019-1967

CWE: 400