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HighKEV

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

CVE-2020-3118 · Cisco IOS XR Software · CVSS 8.8 · KEV

In brief

Severity · CVSS
High8.8CVSS 3.1, High
EPSS
12%
CISA KEV
Known exploited, listed since 3 Nov 2021
CERT-FR
No advisory or alert referenced in the catalog
Vendor
Cisco
Published · Modified
·
Last verified

Summary

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).

Weakness: CWE-134, CWE-787

Title, description and the vendor's statements are quoted from the CVE record; a vendor's advisory is summarised in Patcharo's words, with a link.

Affected and fixed versions

Per product and release branch, as the vendor's CVE record and official advisory state them. A fixed release is shown only when a document names it: the vendor's, or CERT-FR's for Check Point, with its source.

1 branch with a published fixed release

Cisco IOS XR Software

Source: cisco-sa-20200205-iosxr-cdp-rceCVE-2020-3118

  1. 7.1
    Affected versionsNot affected
    First fixed release—
  2. 7.0
    Affected versionsListed as affected, releases not specifiedor appropriate SMU
    First fixed release7.0.2 (upcoming)
  3. 6.6
    Affected versions< 6.6.3or appropriate SMU
    First fixed release6.6.3
  4. before 6.6
    Affected versionsListed as affected, releases not specified
    First fixed releaseNot determined: see the vendor's advisory

Remediation

Fix available

Vendor fix

  • IOS XR Software 6.66.6.3

Upgrade to a fixed release listed above for your branch, or to a later fixed release the vendor explicitly supports.

Cisco has released updates that fix this vulnerability; its advisory lists them.

SourceCisco Security Advisory cisco-sa-20200205-iosxr-cdp-rce

Workarounds (vendor)

Cisco states in its advisory that no workaround is available.

SourceCisco Security Advisory cisco-sa-20200205-iosxr-cdp-rce

CISA KEV required action

Apply updates per vendor instructions.

CISA due date:

SourceCISA KEV

Last verified 1 Oct 2026 at 09:30 UTC

Known exploitation

Added to CISA KEV on 3 Nov 2021

Federal remediation due date: 3 May 2022

The CISA required action is shown under Remediation.

12% probability of exploitation in the next 30 days (percentile 96%).

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CERT-FR

No CERT-FR advisory or alert of the last two years references this CVE, for the vendors Patcharo covers.

Timeline

  1. Published by the source
  2. Added to CISA KEV
  3. CISA remediation due date
  4. Source record last modified
  5. EPSS score computed
  6. Last verified by Patcharo

Official sources

Vendor advisory

References

Cisco · CISA Known Exploited Vulnerabilities · NVD · FIRST EPSS · Cisco Security Advisory cisco-sa-20200205-iosxr-cdp-rce

How Patcharo reads this

Affected and fixed releases come from the vendor's structured statements and are matched against exact versions; CVSS from NVD, exploitation from CISA KEV and the vendor's own advisory, probability from FIRST EPSS. Missing data stays Unknown and never becomes Not affected.

Read the methodologyRead the guide: Cisco Secure Firewall release trains: Threat Defense, Management Center and ASA versions explained