CVE-2020-3118 HIGH

CVE-2020-3118: Cisco IOS XR Software Cisco Discovery Protocol Format String Vulnerability

Vendor Cisco
Product Cisco IOS XR Software
Weakness CWE-134
KEV Status Known Exploited
Published February 5, 2020
Last update October 21, 2025

CVSS base score

8.8/10
Attack vector Adjacent
Attack complexity Low
Privileges required None
User interaction None
Confidentiality High
Integrity High

CVSS vector

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

What the vulnerability does

01Description

A vulnerability in the Cisco Discovery Protocol implementation for Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to execute arbitrary code or cause a reload on an affected device. The vulnerability is due to improper validation of string input from certain fields in 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 cause a stack overflow, which could allow the attacker to execute arbitrary code with administrative privileges on an affected device. 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).

CISA mandated remediation

02CISA Required Action

Apply updates per vendor instructions.

Key dates

03Disclosure timeline

February 5, 2020 CVE published
October 21, 2025 Record updated