dbcve.org
Nx OsOperating system · Cisco

CVE-2018-0090

HIGH · 7.5 CVSS v3.0 Published 2018-01-18
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable 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 management interface access control list (ACL) configuration of Cisco NX-OS System Software could allow an unauthenticated, remote attacker to bypass configured ACLs on the management interface. This could allow traffic to be forwarded to the NX-OS CPU for processing, leading to high CPU utilization and a denial of service (DoS) condition. The vulnerability is due to a bad code fix in the 7.3.2 code train that could allow traffic to the management interface to be misclassified and not match the proper configured ACLs. An attacker could exploit this vulnerability by sending crafted traffic to the management interface. An exploit could allow the attacker to bypass the configured management interface ACLs and impact the CPU of the targeted device, resulting in a DoS condition. This vulnerability affects the following Cisco products running Cisco NX-OS System Software: Multilayer Director Switches, Nexus 2000 Series Switches, Nexus 3000 Series Switches, Nexus 5500 Platform Switches, Nexus 5600 Platform Switches, Nexus 6000 Series Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, Nexus 9000 Series Switches in standalone NX-OS mode. Cisco Bug IDs: CSCvf31132.

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 management interface ACL configuration allows unauthenticated remote attackers to bypass configured ACLs. The issue stems from a faulty code fix in the 7.3.2 code train that causes traffic to the management interface to be misclassified and fail to match properly configured ACLs. This enables crafted traffic to reach the NX-OS CPU, resulting in high CPU utilization and denial of service.

MitigationApply the Cisco software fix for this vulnerability (refer to Cisco Bug CSCvf31132 for patch availability). Until patched, consider network segmentation to restrict management interface exposure and implement additional monitoring for anomalous CPU utilization on the management plane.

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:= 7.3\(2\)n1\(0.6\)= 8.3\(0\)kms\(0.31\)= 8.8\(3.5\)s0

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.0/AV:N/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 NX-OS version
    Execute `show version` on the device CLI and locate the system IOS version line
    Affected if version matches exactly 7.3(2)n1(0.6), 8.3(0)kms(0.31), or 8.8(3.5)s0
  2. Verify management interface exists
    Execute `show interface mgmt0` to confirm the management interface is present and up
    Affected if management interface mgmt0 is configured and operational
  3. Check for management interface ACLs
    Execute `show running-config interface mgmt0` to view ACL applied to management interface
    Affected if an IP access-list is applied to the management interface (this is required for the bypass to be exploitable)
  4. Confirm ACL entries exist
    Execute `show ip access-lists` and locate the ACL name applied to mgmt0, then verify it contains permit or deny rules
    Affected if ACL applied to mgmt0 contains entries (the bypass only matters when ACL rules exist to bypass)
  5. Monitor for unexpected CPU behavior
    Execute `show system resources` or `show processes cpu history` to observe CPU utilization patterns
    Affected if sustained high CPU utilization on management plane with no corresponding legitimate management traffic spike

You are affected only if your NX-OS version exactly matches one of the three affected versions AND you have ACLs configured on the management interface that could be bypassed

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 the Cisco software fix for this vulnerability (refer to Cisco Bug CSCvf31132 for patch availability). Until patched, consider network segmentation to restrict management interface exposure and implement additional monitoring for anomalous CPU utilization on the management plane.

Fix this in Nx Os Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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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-2018-0090 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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