High 8.8Known exploited (CISA KEV)Published Feb 5, 2020

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

Updated under an hour ago (2026-10-19 08:20 UTC)

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It affects Cisco IOS XR Software and 1 other product. Add what you run to find out whether that includes you.

CISA lists it as known exploited since Nov 3, 2021; federal agencies had to remediate by May 3, 2022. Treat that date as your deadline.

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Exploited in the last 30 days

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: 8.8 HIGH (v3.0, CNA)CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-134
Known exploited: Added to CISA KEV Nov 3, 2021; federal remediation due May 3, 2022Apply updates per vendor instructions.
EPSS (exploitation in the next 30 days): 11.68% (percentile 96)
Assigned by: cisco
NVD analysis: Analyzed
Record last updated: Oct 21, 2025
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Cisco Cisco IOS XR Software cisco:ios_xr_software (from the name)	from unspecified before 6.6.3	CNA record
cisco ios_xr cisco:ios_xr	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	NVD

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20200205-iosxr-cdp-rcevendor-advisory, x-refsource-cisco
http://packetstormsecurity.com/files/156203/Cisco-Discovery-Protocol-CDP-Remote-Device-Takeover.htmlx-refsource-misc, third-party-advisory, vdb-entry
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-3118us-government-resource

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.