CVE-2020-3120: Cisco FXOS, IOS XR, and NX-OS Software Cisco Discovery Protocol Denial of Service Vulnerability

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-02-05 · updated 2026-06-17
Weakness: CWE-190

Description

A vulnerability in the Cisco Discovery Protocol implementation for Cisco FXOS Software, Cisco IOS XR Software, and Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to cause a reload of an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to a missing check when the affected software processes Cisco Discovery Protocol messages. An attacker could exploit this vulnerability by sending a malicious Cisco Discovery Protocol packet to an affected device. A successful exploit could allow the attacker to exhaust system memory, causing the device to reload. Cisco Discovery Protocol is a Layer 2 protocol. To exploit this vulnerability, an attacker must be in the same broadcast domain as the affected device (Layer 2 adjacent).

Affected products

Cisco Firepower Extensible Operating System (FXOS): through 2.3.1.173; from 2.6 before 2.6.1.187; from 2.7 before 2.7.1.106 — fixed in 2.6.1.187, 2.7.1.106
Cisco Fxos: 2.4
Cisco IOS XR Software: 5.2.5, 6.4.2, 6.5.3, 6.6.25, 7.0.1
Cisco NX-OS: from 5.2 before 6.2\(29\); from 7.3 before 8.4\(1a\); from 5.2 before 5.2\(1\)sv5\(1.3\); through 5.2; before 5.2\(1\)sv3\(4.1b\); from 7.0\(3\)f2 before 9.3\(2\) — fixed in 13.2\(9b\), 14.2\(1j\), 5.2\(1\)sv3\(4.1b\), 5.2\(1\)sv5\(1.3\), 6.2\(24\), 6.2\(29\)
Cisco Ucs Manager: before 3.2\(3m\); from 4.0 before 4.0\(4g\) — fixed in 3.2\(3m\), 4.0\(4g\)

How to fix

Upgrade to a fixed version: Cisco Firepower Extensible Operating System (FXOS) 2.6.1.187, 2.7.1.106; Cisco NX-OS 13.2\(9b\), 14.2\(1j\), 5.2\(1\)sv3\(4.1b\), 5.2\(1\)sv5\(1.3\); Cisco Ucs Manager 3.2\(3m\), 4.0\(4g\). Check the vendor advisory for mitigations.

References

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