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

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: yes — in CISA KEV since 2021-11-03
EPSS: 11.7% 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-134

Description

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).

Affected products

Cisco IOS XR Software: from 6.6.0 before 6.6.12; from 7.0.0 before 7.0.2; 6.5.3, 5.2.5, 6.4.2, 6.6.25, 7.0.1 — fixed in 6.6.12, 7.0.2

How to fix

Upgrade to a fixed version: Cisco IOS XR Software 6.6.12, 7.0.2. Check the vendor advisory for mitigations.

References

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