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CVE-2020-3118

KEVCisco IOS XR Software Discovery Protocol Format String Vulnerability

Cisco IOS XR improperly validates string input from certain fields in Cisco Discovery Protocol messages. Exploitation could allow an unauthenticated, adjacent attacker to execute code with administrative privileges or cause a reload on an affected device.

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).

CVSS 3.1 vectorCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
PublishedFeb 5, 2020
Last modifiedJun 17, 2026
Added to KEVNov 3, 2021
Remediation dueMay 3, 2022
    75
    Risk assessment · High

    Actively exploited. Patch immediately.

    Exploitation
    Confirmed in the wild (CISA KEV)
    Federal remediation deadline
    Overdue by 1637 days
    CVSS
    8.8 HIGH
    EPSS (30-day exploit probability)
    11.7% · top 4% of all CVEs
    Weakness
    CWE-134
    Preconditions
    No privileges and no user interaction
    1. 1.Apply updates per vendor instructions.
    2. 2.Treat as emergency change: patch or isolate internet-facing instances first.
    3. 3.Hunt for compromise: review logs for the disclosure window, not just from the patch date.

    Assessment is derived automatically from the live signals above; verify against your own asset inventory.