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Nexus 7000 FirmwareOperating system · Cisco

CVE-2018-0304

CRITICAL · 9.8 CVSS v3.0 Published 2018-06-20
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
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 the Cisco Fabric Services component of Cisco FXOS Software and Cisco NX-OS Software could allow an unauthenticated, remote attacker to read sensitive memory content, create a denial of service (DoS) condition, or execute arbitrary code as root. The vulnerability exists because the affected software insufficiently validates Cisco Fabric Services packet headers. An attacker could exploit this vulnerability by sending a crafted Cisco Fabric Services packet to an affected device. A successful exploit could allow the attacker to cause a buffer overflow or buffer overread condition in the Cisco Fabric Services component, which could allow the attacker to read sensitive memory content, create a DoS condition, or execute arbitrary code as root. This vulnerability affects the following if configured to use Cisco Fabric Services: Firepower 4100 Series Next-Generation Firewalls, Firepower 9300 Security Appliance, MDS 9000 Series Multilayer Switches, Nexus 2000 Series Fabric Extenders, Nexus 3000 Series Switches, Nexus 3500 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, UCS 6100 Series Fabric Interconnects, UCS 6200 Series Fabric Interconnects, UCS 6300 Series Fabric Interconnects. Cisco Bug IDs: CSCvd69951, CSCve02459, CSCve02461, CSCve02463, CSCve02474, CSCve04859.

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

Buffer overflow/overread vulnerability in Cisco Fabric Services packet header validation allows unauthenticated remote attackers to read sensitive memory, cause DoS, or execute arbitrary code as root on affected Firepower appliances, MDS switches, Nexus switches (multiple series), and UCS Fabric Interconnects running FXOS or NX-OS software.

MitigationApply Cisco security patches for affected FXOS and NX-OS versions; if patches unavailable, restrict network access to Cisco Fabric Services ports or implement network segmentation to limit exposure to untrusted networks.

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
Nexus 7000 FirmwareOperating system
Affected:= 7.3\(2\)d1\(0.49\)= 8.0\(1\)= 8.1\(0.112\)s0
Nexus 5000 FirmwareOperating system
Affected:= 7.0\(0\)hsk\(0.357\)= 7.3\(0\)d1\(0.98\)= 8.1\(0.2\)s0
Firepower 9000 FirmwareOperating system
Affected:= r211= r231
Nexus 9000 FirmwareOperating system
Affected:= 8.1\(0\)bd\(0.20\)= 8.1\(1\)s4
Unified Computing System FirmwareOperating system
Affected:= 3.1\(3a\)a= 7.0\(0\)hsk\(0.357\)

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
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/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. Identify the running firmware version
    Use 'show version' or check the device management interface to determine the exact firmware/OS version (FXOS or NX-OS) installed on the Cisco device
    Affected if The installed version matches one of the listed affected versions: 7.3(2)d1(0.49), 8.0(1), 8.1(0.112)s0 for Nexus 7000; 7.0(0)hsk(0.357), 7.3(0)d1(0.98), 8.1(0.2)s0 for Nexus 5000; r211, r231 for Firepower 9000; 8.1(0)bd(0.20), 8.1(1)s4 for Nexus 9000; 3.1(3a)a, 7.0(0)hsk(0.357) for UCS Firmware
  2. Confirm Cisco Fabric Services is enabled
    Check the device configuration for 'fabric services' or 'cfs' related settings using 'show running-config | include cfs' or 'show cfs status' commands
    Affected if Cisco Fabric Services (CFS) is enabled on the device - the vulnerability only applies when this feature is active
  3. Verify network accessibility of Fabric Services ports
    Identify which ports Fabric Services uses (typically port 1741 for CFS over TCP) and check if these ports are exposed to untrusted networks using 'show ip interface' and network access control lists
    Affected if Fabric Services ports are reachable from untrusted network segments - the vulnerability is remotely exploitable when the service is network-accessible to unauthenticated attackers

A device is affected if it runs one of the listed firmware versions AND has Cisco Fabric Services enabled AND the service is accessible from untrusted networks.

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 security patches for affected FXOS and NX-OS versions; if patches unavailable, restrict network access to Cisco Fabric Services ports or implement network segmentation to limit exposure to untrusted networks.

Fix this in Nexus 7000 Firmware Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA4.0 h
40.0 hours of engineering $7,000
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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-2018-0304 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