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Nx OsOperating system · Cisco

CVE-2018-0306

HIGH · 7.8 CVSS v3.1 Published 2018-06-21
Fix available
A fix is available. Upgrade to 5.2 / 7.3 or later.
See remediation →
80/100
Remediation priority · High
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 CLI parser of Cisco NX-OS Software could allow an authenticated, local attacker to perform a command-injection attack on an affected device. The vulnerability is due to insufficient input validation of command arguments. An attacker could exploit this vulnerability by injecting malicious command arguments into a vulnerable CLI command. A successful exploit could allow the attacker to execute arbitrary commands with root privileges on the affected device. Note: This vulnerability requires that any feature license is uploaded to the device. The vulnerability does not require that the license be used. This vulnerability affects MDS 9000 Series Multilayer Switches, Nexus 1000V Series Switches, Nexus 1100 Series Cloud Services Platforms, Nexus 2000 Series Fabric Extenders, Nexus 3000 Series Switches, Nexus 3500 Platform Switches, Nexus 3600 Platform 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, Nexus 9500 R-Series Line Cards and Fabric Modules. Cisco Bug IDs: CSCve51693, CSCve91634, CSCve91659, CSCve91663.

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 command injection vulnerability exists in the CLI parser of Cisco NX-OS Software. An authenticated local attacker with access to the device CLI can inject malicious command arguments into vulnerable CLI commands due to insufficient input validation. Successful exploitation grants the attacker arbitrary command execution with root privileges on the affected device. The attack requires that a feature license file is present on the device (uploaded but not necessarily active).

MitigationApply the Cisco patches for CVE-2018-0306 corresponding to the specific NX-OS version running on affected devices. Until patches are applied, restrict local administrative access to trusted personnel only and remove unused feature license files to reduce the 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:< 7.3\(3\)n1\(1\)= 8.1\(0.2\)s0= 8.1\(0\)bd\(0.20\)= 8.1\(0.59\)s0= 8.1\(1\)= 6.0\(2\)a8\(3\)< 5.2\(1\)sv3\(3.15\)< 8.1\(1a\)

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

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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. Determine NX-OS version
    Run 'show version' command in the device CLI and locate the NX-OS release string in the output
    Affected if The version matches any of these patterns: < 7.3(3)n1(1), = 8.1(0.2)s0, = 8.1(0)bd(0.20), = 8.1(0.59)s0, = 8.1(1), = 6.0(2)a8(3), < 5.2(1)sv3(3.15), or < 8.1(1a)
  2. Verify presence of feature license files
    Run 'show license' command in the CLI to list installed license files, or check the bootflash: directory for .lic files
    Affected if Any feature license file is present on the device (uploaded license files, whether active or inactive)
  3. Confirm license file type
    Examine the license file names or run 'show license usage' to identify if they are feature licenses versus base licenses
    Affected if Feature license files are present (as opposed to only base/default licenses)

A device is affected if it runs a vulnerable NX-OS version listed above AND has at least one feature license file present on the system.

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
Upgrade available Upgrade to 5.2 / 7.3 / 8.1 or later
Fixed in 5.27.38.1
Interim mitigation

Apply the Cisco patches for CVE-2018-0306 corresponding to the specific NX-OS version running on affected devices. Until patches are applied, restrict local administrative access to trusted personnel only and remove unused feature license files to reduce the attack surface.

Fix this in Nx Os Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2018-0306 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