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Nx OsOperating system · Cisco

CVE-2023-20089

MEDIUM · 6.5 CVSS v3.1 Published 2023-02-23
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
70/100
Remediation priority · Elevated
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 Link Layer Discovery Protocol (LLDP) feature for Cisco Nexus 9000 Series Fabric Switches in Application Centric Infrastructure (ACI) Mode could allow an unauthenticated, adjacent attacker to cause a memory leak, which could result in an unexpected reload of the device. This vulnerability is due to incorrect error checking when parsing ingress LLDP packets. An attacker could exploit this vulnerability by sending a steady stream of crafted LLDP packets to an affected device. A successful exploit could allow the attacker to cause a memory leak, which could result in a denial of service (DoS) condition when the device unexpectedly reloads. Note: This vulnerability cannot be exploited by transit traffic through the device. The crafted LLDP packet must be targeted to a directly connected interface, and the attacker must be in the same broadcast domain as the affected device (Layer 2 adjacent). In addition, the attack surface for this vulnerability can be reduced by disabling LLDP on interfaces where it is not required.

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 memory leak vulnerability exists in the LLDP feature of Cisco Nexus 9000 Series Fabric Switches in ACI Mode. The flaw stems from incorrect error checking during parsing of ingress LLDP packets. An unauthenticated, adjacent attacker sending a steady stream of crafted LLDP packets to a directly connected interface can trigger the memory leak, causing the device to unexpectedly reload.

MitigationDisable LLDP on interfaces where it is not required to reduce the attack surface. Apply the Cisco-provided firmware patch when available to address the underlying parsing flaw.

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:= 15.2\(1g\)= 15.2\(2e\)= 15.2\(2f\)= 15.2\(2g\)= 15.2\(2h\)= 15.2\(3e\)= 15.2\(3f\)= 15.2\(3g\)= 15.2\(4d\)= 15.2\(4e\)= 15.2\(4f\)= 15.2\(5c\)

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
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/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 device model and mode
    Run 'show version' and 'show running-config | include "mode"' or 'show system mode' to confirm the device is a Cisco Nexus 9000 Series Fabric Switch running in ACI Mode.
    Affected if Device is not a Nexus 9000 Series in ACI Mode, then this CVE does not apply.
  2. Check NX-OS version
    Run 'show version' to display the installed NX-OS software version.
    Affected if Version matches 15.2(1g), 15.2(2e), 15.2(2f), 15.2(2g), 15.2(2h), 15.2(3e), 15.2(3f), 15.2(3g), 15.2(4d), 15.2(4e), 15.2(4f), or 15.2(5c).
  3. Verify LLDP is enabled
    Run 'show lldp neighbors' or 'show lldp interface' to check if LLDP is operational on any interfaces.
    Affected if LLDP is enabled on one or more interfaces, the device is potentially vulnerable to the memory leak when crafted packets are received.
  4. Review LLDP interface configuration
    Run 'show running-config | include lldp' to see all LLDP-related configuration across interfaces.
    Affected if LLDP receive or transmit is configured on any interface, the attack surface exists.

Device is affected if it is a Nexus 9000 Series in ACI Mode running one of the listed versions AND LLDP is enabled on at least one interface.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Disable LLDP on interfaces where it is not required to reduce the attack surface. Apply the Cisco-provided firmware patch when available to address the underlying parsing flaw.

Fix this in Nx Os Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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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-2023-20089 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
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