CVE-2020-3120

What it is

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).

At a glance

Exploitability

Can be exploited from the same network segment without logging in. High risk of service disruption.

Exploit odds

1.6% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2020-02-05 18:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-06-17 03:17 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 1.6% in the next 30 days (EPSS).
• Severity: 6.5 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2020-02-05 18:15 UTC

Last modified

2026-06-17 03:17 UTC

Exploit probability

1.6% · EPSS, next 30 days

Weakness

CWE-190 · Integer overflow

Record status

Modified

Affected

• Cisco Firepower Extensible Operating System ≤ 2.3.1.173
• Cisco Firepower Extensible Operating System < 2.6.1.187
• Cisco Firepower Extensible Operating System < 2.7.1.106
• Cisco Fxos 2.4
• Cisco iOS Xr 5.2.5
• Cisco iOS Xr 6.4.2
• Cisco iOS Xr 6.5.3
• Cisco iOS Xr 6.6.25

Attack profile CVSS 3.1 · 6.5

Attack vector

Adjacent network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2020-3120.md and follow it. Check whether this project is affected by CVE-2020-3120. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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