dbcve.org
Nx OsOperating system · Cisco

CVE-2023-20169

HIGH · 7.4 CVSS v3.1 Published 2023-08-23
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
79/100
Remediation priority · High
No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A vulnerability in the Intermediate System-to-Intermediate System (IS-IS) protocol of Cisco NX-OS Software for the Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches in standalone NX-OS mode could allow an unauthenticated, adjacent attacker to cause the IS-IS process to unexpectedly restart, which could cause an affected device to reload. This vulnerability is due to insufficient input validation when parsing an ingress IS-IS packet. An attacker could exploit this vulnerability by sending a crafted IS-IS packet to an affected device. A successful exploit could allow the attacker to cause a denial of service (DoS) condition due to the unexpected restart of the IS-IS process, which could cause the affected device to reload. Note: The IS-IS protocol is a routing protocol. To exploit this vulnerability, an attacker must be Layer 2 adjacent to the affected device.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A vulnerability in Cisco NX-OS Software for Nexus 3000 and 9000 Series switches allows an unauthenticated, Layer 2 adjacent attacker to send a crafted IS-IS packet that triggers insufficient input validation during packet parsing, causing the IS-IS process to unexpectedly restart and the device to reload.

MitigationApply the Cisco vendor patch when available. Until then, limit Layer 2 adjacency to trusted devices and consider filtering IS-IS traffic at network boundaries to reduce attack surface.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Nx OsOperating system
Affected:= 10.3\(2\)

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the NX-OS version running on the device
    Execute 'show version' or 'show version | include NXOS' in the NX-OS CLI to retrieve the installed software version
    Affected if The version displayed is exactly 10.3(2)
  2. Verify if IS-IS protocol is enabled
    Execute 'show isis status' or 'show protocol' in the NX-OS CLI to check whether the IS-IS process is running on any interface
    Affected if IS-IS is active and running on one or more interfaces (vulnerable only if IS-IS is enabled)
  3. Confirm the specific version string matches the affected release
    Locate the exact version number in the 'show version' output (typically shown as 'NXOS: version 10.3(2)' or similar)
    Affected if The version string is exactly 10.3(2) AND IS-IS is enabled

The device is affected only if it runs NX-OS version 10.3(2) exactly AND has IS-IS protocol enabled and processing traffic on Layer 2 adjacent network segments.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Cisco vendor patch when available. Until then, limit Layer 2 adjacency to trusted devices and consider filtering IS-IS traffic at network boundaries to reduce attack surface.

Recommended fix Moderate confidence

Fixed NX-OS release as specified in the Cisco security advisory for CVE-2023-20169 (obtain from sec.cloudapps.cisco.com)

  1. 1. Identify the Cisco Nexus 3000 Series or Nexus 9000 Series switch currently running NX-OS version 10.3(2)
  2. 2. Access the Cisco Security Advisories page at sec.cloudapps.cisco.com and search for CVE-2023-20169
  3. 3. Locate the fixed NX-OS release for your specific switch model
  4. 4. Download the appropriate fixed NX-OS software version from the Cisco software download center
  5. 5. Plan an upgrade window following Cisco NX-OS upgrade best practices, including backing up the current configuration
  6. 6. Upgrade the device to the fixed NX-OS version using the standard upgrade procedure for your platform
  7. 7. Verify the IS-IS process is running normally after the upgrade
  8. 8. Confirm the device is no longer vulnerable by validating the new NX-OS version
Caveat Review Cisco NX-OS release notes for any known issues or configuration changes between 10.3(2) and the fixed release before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Nx Os Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-20169 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data