dbcve.org
Application Policy Infrastructure ControllerApplication · Cisco

CVE-2019-1890

MEDIUM · 6.5 CVSS v3.1 Published 2019-07-04
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 fabric infrastructure VLAN connection establishment of the Cisco Nexus 9000 Series Application Centric Infrastructure (ACI) Mode Switch Software could allow an unauthenticated, adjacent attacker to bypass security validations and connect an unauthorized server to the infrastructure VLAN. The vulnerability is due to insufficient security requirements during the Link Layer Discovery Protocol (LLDP) setup phase of the infrastructure VLAN. An attacker could exploit this vulnerability by sending a malicious LLDP packet on the adjacent subnet to the Cisco Nexus 9000 Series Switch in ACI mode. A successful exploit could allow the attacker to connect an unauthorized server to the infrastructure VLAN, which is highly privileged. With a connection to the infrastructure VLAN, the attacker can make unauthorized connections to Cisco Application Policy Infrastructure Controller (APIC) services or join other host endpoints.

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 Nexus 9000 Series ACI Mode switches allows unauthenticated adjacent attackers to bypass security validations during the LLDP setup phase of the infrastructure VLAN. By sending malicious LLDP packets on the adjacent subnet, attackers can connect unauthorized servers to the highly privileged infrastructure VLAN, enabling unauthorized APIC service connections and host endpoint joins.

MitigationApply Cisco's patch for this vulnerability when available; otherwise, implement strict LLDP authentication/validation controls and network segmentation to limit exposure of the infrastructure VLAN to adjacent subnets.

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
Application Policy Infrastructure ControllerApplication
Affected:= 7.3\(0\)zn\(0.113\)

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
High
Availability
None

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

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 if running Cisco APIC or Nexus 9000 Series ACI Mode
    Check the device model and firmware version using 'show version' or access the APIC GUI and navigate to Admin > System Settings > Controller Version
    Affected if Device is Cisco Application Policy Infrastructure Controller version 7.3(0)zn(0.113) or Cisco Nexus 9000 Series switch in ACI mode
  2. Verify APIC controller version
    On the APIC GUI, go to Admin > System Settings > Controller Version to confirm the exact version, or run 'show version' on Nexus 9000 CLI
    Affected if Version equals exactly 7.3(0)zn(0.113)
  3. Check LLDP configuration on infrastructure VLAN
    Run 'show lldp neighbor' and 'show run lldp' on the Nexus 9000 switch to see LLDP status and neighbors, or check APIC GUI under Fabric > Inventory > Pod > LLDP
    Affected if LLDP is enabled on the infrastructure VLAN interface
  4. Inspect infrastructure VLAN network exposure
    Check the VLAN configuration with 'show vlan' and verify if infrastructure VLAN (typically VLAN 1 or dedicated infra VLAN) is trunked to access ports or exposed to adjacent subnets
    Affected if Infrastructure VLAN is accessible from adjacent/trunk ports without strict port security
  5. Audit LLDP neighbors for unauthorized devices
    Review output from 'show lldp neighbor detail' and compare against expected APIC and leaf switch MAC addresses, or check APIC GUI for unexpected LLDP entries under Fabric > Inventory
    Affected if Unexpected or unauthorized LLDP neighbors are present on infrastructure VLAN ports

Affected if running APIC version 7.3(0)zn(0.113) or Nexus 9000 ACI Mode with LLDP enabled on infrastructure VLAN exposed to adjacent subnets.

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

Apply Cisco's patch for this vulnerability when available; otherwise, implement strict LLDP authentication/validation controls and network segmentation to limit exposure of the infrastructure VLAN to adjacent subnets.

Fix this in Application Policy Infrastructure Controller Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,224.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2019-1890 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2019-1890 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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