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Nexus 7000 FirmwareOperating system · Cisco

CVE-2018-0312

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 execute arbitrary code or cause a denial of service (DoS) condition on an affected device. The vulnerability exists because the affected software insufficiently validates Cisco Fabric Services packet headers when the software processes packet data. An attacker could exploit this vulnerability by sending a maliciously crafted Cisco Fabric Services packet to an affected device. A successful exploit could allow the attacker to cause a buffer overflow condition on the device, which could allow the attacker to execute arbitrary code or cause a DoS condition on the device. 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: CSCvd69962, CSCve02808, CSCve02810, CSCve02812, CSCve02819, CSCve02822, CSCve02831, 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

A buffer overflow vulnerability exists in Cisco Fabric Services component of FXOS and NX-OS software due to insufficient validation of packet headers. An unauthenticated remote attacker can send a maliciously crafted Cisco Fabric Services packet to trigger the buffer overflow, potentially allowing arbitrary code execution or causing a denial of service on affected devices.

MitigationApply the relevant Cisco software updates corresponding to the Bug IDs (CSCvd69962, CSCve02808, CSCve02810, CSCve02812, CSCve02819, CSCve02822, CSCve02831, CSCve04859). As an interim measure, restrict network access to the Cisco Fabric Services ports and isolate affected devices behind network segmentation until patches can be applied.

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\(0.357\)
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

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 device model and firmware version
    Execute 'show version' on the NX-OS/FXOS CLI or check via Cisco UCS Manager. Note the exact firmware version string (e.g., 7.3(2)d1(0.49), 8.0(1), 8.1(0.112)s0 for Nexus 7000).
    Affected if The device is a Nexus 7000, Nexus 5000, Nexus 9000, Firepower 9000, or UCS system running one of the specific versions listed (7.3(2)d1(0.49), 8.0(1), 8.1(0.112)s0, 7.0(0)hsk(0.357), r211, r231, 8.1(0)bd(0.20), 8.1(1)s4, or 3.1(3a)a).
  2. Verify Cisco Fabric Services is enabled
    Check if the Cisco Fabric Services daemon is running. On NX-OS, use 'show process | include cfs' or check for port 4786 (UDP/TCP) listening with 'show ip socket' or 'netstat -an | grep 4786'.
    Affected if The Cisco Fabric Services process is active and the service is listening for incoming connections on the device.
  3. Confirm network accessibility of Fabric Services ports
    Verify that UDP port 4786 and TCP port 4786 are exposed to untrusted networks. Check with 'show access-lists' and review any firewall or ACL configurations that might allow external access to these ports.
    Affected if The device has Cisco Fabric Services ports (4786/UDP and 4786/TCP) reachable from untrusted network segments, allowing an unauthenticated remote attacker to send malicious packets.

A user is affected if they run one of the listed firmware versions on Nexus 7000, 5000, 9000, Firepower 9000, or UCS platforms AND the Cisco Fabric Services is active and accessible from the network.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the relevant Cisco software updates corresponding to the Bug IDs (CSCvd69962, CSCve02808, CSCve02810, CSCve02812, CSCve02819, CSCve02822, CSCve02831, CSCve04859). As an interim measure, restrict network access to the Cisco Fabric Services ports and isolate affected devices behind network segmentation until patches can be applied.

Recommended fix Moderate confidence

Contact Cisco Technical Support for platform-specific fixed releases; no specific fixed version provided in advisory

  1. 1. Identify all Cisco devices running the affected firmware versions in your environment (Nexus 7000/5000/9000, Firepower 9000, UCS platforms).
  2. 2. Verify whether Cisco Fabric Services is enabled on affected devices, as this vulnerability only affects devices configured to use Cisco Fabric Services.
  3. 3. Contact Cisco Technical Support or check the Cisco Security Advisories page for the most current fixed software versions for your specific product model.
  4. 4. Download the appropriate fixed firmware version from Cisco.com or the Cisco Software Download center.
  5. 5. Schedule a maintenance window as upgrades may require device reloads.
  6. 6. Back up current device configurations before applying the upgrade.
  7. 7. Apply the upgraded firmware following standard Cisco upgrade procedures for your platform.
  8. 8. After upgrade, verify the device is functioning correctly and the vulnerability is remediated.
Caveat Review Cisco release notes for your specific platform for any potential compatibility or behavioral changes between your current and fixed version

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Nexus 7000 Firmware Scoped from the published advisory
  • Consultation8.0 h
  • Implementation24.0 h
  • Testing16.0 h
  • Review / QA8.0 h
56.0 hours of engineering $9,760
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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-2018-0312 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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