CVE-2026-20173
Received Received - Intake

Denial of Service in Cisco NX-OS Software

Publication date: 2026-10-07

Last updated on: 2026-10-07

Assigner: Cisco Systems, Inc.

Description
A vulnerability in Cisco NX-OS Software could allow an unauthenticated, remote attacker to exhaust system resources, causing a denial of service (DoS) condition. This vulnerability exists because rate limiting was improperly applied to some protocols. An attacker could exploit this vulnerability by sending a high rate of UDP or TCP connections to a data plane interface on an affected device. A successful exploit could allow the attacker to cause instability to various routing and control plane protocols through some packet loss and temporary disruptions, causing a DoS condition. This DoS condition will clear without manual intervention soon after the high rate of traffic is stopped.

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Meta Information

Published
2026-10-07
Last Modified
2026-10-07
Generated
2026-10-07
AI Q&A
2026-10-07
EPSS Evaluated
N/A
NVD
CVE-2026-20173
EUVD
EUVD-2026-94449

Affected Vendors & Products

Showing 111 associated CPEs
Vendor Product Version / Range
Cisco Cisco NX-OS Software 8.2(5)
Cisco Cisco NX-OS Software 7.3(5)D1(1)
Cisco Cisco NX-OS Software 8.4(2)
Cisco Cisco NX-OS Software 8.4(3)
Cisco Cisco NX-OS Software 9.2(3)
Cisco Cisco NX-OS Software 9.2(2v)
Cisco Cisco NX-OS Software 7.3(4)D1(1)
Cisco Cisco NX-OS Software 8.2(1)
Cisco Cisco NX-OS Software 9.2(1)
Cisco Cisco NX-OS Software 9.2(2t)
Cisco Cisco NX-OS Software 9.2(3y)
Cisco Cisco NX-OS Software 9.3(2)
Cisco Cisco NX-OS Software 8.1(1)
Cisco Cisco NX-OS Software 8.2(2)
Cisco Cisco NX-OS Software 8.3(2)
Cisco Cisco NX-OS Software 7.3(2)D1(3a)
Cisco Cisco NX-OS Software 9.2(4)
Cisco Cisco NX-OS Software 8.1(2)
Cisco Cisco NX-OS Software 7.3(3)D1(1)
Cisco Cisco NX-OS Software 8.2(3)
Cisco Cisco NX-OS Software 8.4(1)
Cisco Cisco NX-OS Software 7.3(0)DX(1)
Cisco Cisco NX-OS Software 7.3(2)D1(1)
Cisco Cisco NX-OS Software 9.3(1)
Cisco Cisco NX-OS Software 7.3(2)D1(2)
Cisco Cisco NX-OS Software 8.2(4)
Cisco Cisco NX-OS Software 9.3(1z)
Cisco Cisco NX-OS Software 9.2(2)
Cisco Cisco NX-OS Software 8.1(2a)
Cisco Cisco NX-OS Software 7.3(2)D1(3)
Cisco Cisco NX-OS Software 8.3(1)
Cisco Cisco NX-OS Software 7.3(1)D1(1)
Cisco Cisco NX-OS Software 7.3(0)D1(1)
Cisco Cisco NX-OS Software 9.3(3)
Cisco Cisco NX-OS Software 7.3(2)D1(1d)
Cisco Cisco NX-OS Software 9.3(4)
Cisco Cisco NX-OS Software 7.3(6)D1(1)
Cisco Cisco NX-OS Software 8.2(6)
Cisco Cisco NX-OS Software 9.3(5)
Cisco Cisco NX-OS Software 9.3(6)
Cisco Cisco NX-OS Software 8.4(4)
Cisco Cisco NX-OS Software 7.3(7)D1(1)
Cisco Cisco NX-OS Software 9.3(5w)
Cisco Cisco NX-OS Software 8.2(7)
Cisco Cisco NX-OS Software 9.3(7)
Cisco Cisco NX-OS Software 9.3(7k)
Cisco Cisco NX-OS Software 7.3(8)D1(1)
Cisco Cisco NX-OS Software 9.3(7a)
Cisco Cisco NX-OS Software 8.2(7a)
Cisco Cisco NX-OS Software 9.3(8)
Cisco Cisco NX-OS Software 8.4(4a)
Cisco Cisco NX-OS Software 8.4(5)
Cisco Cisco NX-OS Software 8.2(8)
Cisco Cisco NX-OS Software 9.3(9)
Cisco Cisco NX-OS Software 7.3(9)D1(1)
Cisco Cisco NX-OS Software 8.4(6)
Cisco Cisco NX-OS Software 9.3(10)
Cisco Cisco NX-OS Software 8.2(9)
Cisco Cisco NX-OS Software 10.3(1)
Cisco Cisco NX-OS Software 8.4(7)
Cisco Cisco NX-OS Software 10.3(2)
Cisco Cisco NX-OS Software 8.4(6a)
Cisco Cisco NX-OS Software 9.3(11)
Cisco Cisco NX-OS Software 10.3(3)
Cisco Cisco NX-OS Software 8.2(10)
Cisco Cisco NX-OS Software 9.3(12)
Cisco Cisco NX-OS Software 10.4(1)
Cisco Cisco NX-OS Software 8.4(8)
Cisco Cisco NX-OS Software 10.3(99w)
Cisco Cisco NX-OS Software 10.3(3w)
Cisco Cisco NX-OS Software 10.3(99x)
Cisco Cisco NX-OS Software 10.3(3o)
Cisco Cisco NX-OS Software 8.4(9)
Cisco Cisco NX-OS Software 10.3(4)
Cisco Cisco NX-OS Software 10.3(3p)
Cisco Cisco NX-OS Software 10.3(4a)
Cisco Cisco NX-OS Software 10.4(2)
Cisco Cisco NX-OS Software 10.3(3q)
Cisco Cisco NX-OS Software 9.3(13)
Cisco Cisco NX-OS Software 8.2(11)
Cisco Cisco NX-OS Software 10.3(5)
Cisco Cisco NX-OS Software 10.4(3)
Cisco Cisco NX-OS Software 10.3(3x)
Cisco Cisco NX-OS Software 10.3(4g)
Cisco Cisco NX-OS Software 10.5(1)
Cisco Cisco NX-OS Software 8.4(10)
Cisco Cisco NX-OS Software 10.3(3r)
Cisco Cisco NX-OS Software 10.3(6)
Cisco Cisco NX-OS Software 9.3(14)
Cisco Cisco NX-OS Software 10.4(4)
Cisco Cisco NX-OS Software 10.3(4h)
Cisco Cisco NX-OS Software 10.5(2)
Cisco Cisco NX-OS Software 8.4(11)
Cisco Cisco NX-OS Software 10.3(7)
Cisco Cisco NX-OS Software 10.4(5)
Cisco Cisco NX-OS Software 10.5(3)
Cisco Cisco NX-OS Software 9.3(15)
Cisco Cisco NX-OS Software 10.4(4g)
Cisco Cisco NX-OS Software 10.5(4)
Cisco Cisco NX-OS Software 8.4(12)
Cisco Cisco NX-OS Software 10.5(3t)
Cisco Cisco NX-OS Software 10.3(8)
Cisco Cisco NX-OS Software 10.4(6)
Cisco Cisco NX-OS Software 10.5(3s)
Cisco Cisco NX-OS Software 10.5(3e)
Cisco Cisco NX-OS Software 10.5(3o)
Cisco Cisco NX-OS Software 9.3(16)
Cisco Cisco NX-OS Software 10.5(3p)
Cisco Cisco NX-OS Software 10.4(7)
Cisco Cisco NX-OS Software 10.5(5)
Cisco Cisco NX-OS Software 9.3(17)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-770 The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

Attack-Flow Graph

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Executive Summary

This is a medium-severity vulnerability in Cisco NX-OS Software that allows an unauthenticated remote attacker to cause a denial of service by overwhelming system resources. It occurs because rate limiting was not properly applied to certain protocols. Attackers can exploit this by sending excessive UDP or TCP connections to a device's data plane interface, leading to instability in routing and control plane protocols, packet loss, and temporary disruptions.

Detection Guidance

Monitor network traffic for unusually high UDP or TCP connection rates to data plane interfaces on Cisco NX-OS devices. Use tools like Wireshark or tcpdump to capture and analyze traffic patterns. Check system logs for signs of resource exhaustion or protocol instability.

Impact Analysis

This vulnerability can cause network instability, packet loss, and temporary disruptions to routing and control plane protocols. It may lead to degraded network performance or complete outages for affected devices. The impact is temporary and resolves once the excessive traffic stops.

Mitigation Strategies

Upgrade affected Cisco NX-OS devices to the fixed software versions provided by Cisco. If immediate upgrading is not possible, implement network-level controls to limit excessive UDP or TCP traffic to data plane interfaces.

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