CVE-2023-20014 – An unauthenticated remote attacker can cause de... (How to Fix)

Q: What is the severity of CVE-2023-20014?

CVE-2023-20014 has a CVSS score of 7.5 (HIGH). An unauthenticated remote attacker can cause denial of service on Cisco Nexus Dashboard by sending continuous DNS requests. This vulnerability affects the coredns service and can cause service disruption or device reload. Organizations running vulnerable Cisco Nexus Dashboard versions are affected.

📋 TL;DR

An unauthenticated remote attacker can cause denial of service on Cisco Nexus Dashboard by sending continuous DNS requests. This vulnerability affects the coredns service and can cause service disruption or device reload. Organizations running vulnerable Cisco Nexus Dashboard versions are affected.

💻 Affected Systems

Products:

Cisco Nexus Dashboard

Versions: Versions earlier than 2.3(1)

Operating Systems: Cisco Nexus Dashboard OS

Default Config Vulnerable: ⚠️ Yes

Notes: All deployments with DNS functionality enabled are vulnerable

📦 What is this software?

Nexus Dashboard by Cisco

View all CVEs affecting Nexus Dashboard →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete service outage requiring device reboot, disrupting all Nexus Dashboard functionality and dependent services

🟠

Likely Case

Intermittent DNS service disruption affecting device management and monitoring capabilities

🟢

If Mitigated

Minimal impact with proper network segmentation and rate limiting

🌐 Internet-Facing: HIGH

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Simple DNS flood attack requiring no authentication

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 2.3(1) or later

Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ndb-dnsdos-bYscZOsu

Restart Required: Yes

Instructions:

1. Download Nexus Dashboard 2.3(1) or later from Cisco Software Center. 2. Follow Cisco's upgrade procedure for Nexus Dashboard. 3. Reboot the device after upgrade completion.

🔧 Temporary Workarounds

DNS Rate Limiting

all

Implement DNS query rate limiting on network devices

Network Segmentation

all

Restrict DNS traffic to trusted sources only

🧯 If You Can't Patch

Implement strict network ACLs to limit DNS traffic to Nexus Dashboard
Deploy inline DDoS protection for DNS traffic

🔍 How to Verify

Check if Vulnerable:

Check Nexus Dashboard version via web UI or CLI: show version

Check Version:

show version

Verify Fix Applied:

Confirm version is 2.3(1) or later and monitor coredns service stability

📡 Detection & Monitoring

Log Indicators:

High volume of DNS queries in system logs
coredns service restart events
Device reload events

Network Indicators:

Unusual DNS traffic patterns to Nexus Dashboard
DNS flood from single source

SIEM Query:

source="nexus-dashboard" AND ("DNS flood" OR "coredns restart" OR "high DNS queries")

📊 Metadata

CVE ID: CVE-2023-20014

CVSS v3 Score: 7.5 (HIGH)

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

CWE: CWE-399

Published: March 1, 2023

Last Updated: November 21, 2024

🔗 References

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🔗 Related Vulnerabilities

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