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Nx OsOperating system · Cisco

CVE-2018-0372

HIGH · 7.5 CVSS v3.0 Published 2018-07-18
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 the DHCPv6 feature of the Cisco Nexus 9000 Series Fabric Switches in Application-Centric Infrastructure (ACI) Mode could allow an unauthenticated, remote attacker to cause the device to run low on system memory, which could result in a Denial of Service (DoS) condition on an affected system. The vulnerability is due to improper memory management when DHCPv6 packets are received on an interface of the targeted device. An attacker could exploit this vulnerability by sending a high number of malicious DHCPv6 packets to be processed by an affected device. A successful exploit could allow the attacker to cause the system to run low on memory, which could cause an eventual reboot of an affected device. The vulnerability only applies to IPv6 protocol packets and not for IPv4 protocol packets. This vulnerability affects Cisco Nexus 9000 Series Fabric Switches in ACI Mode running software version 13.0(1k). The vulnerability can only be exploited when unicast routing is enabled on the Bridge Domain (BD). DHCP and DHCP relay do not have to be configured for the vulnerability to be exploited. Cisco Bug IDs: CSCvg38918.

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 the DHCPv6 feature of Cisco Nexus 9000 Series Fabric Switches in ACI Mode allows an unauthenticated remote attacker to cause low memory conditions by sending malicious DHCPv6 packets, potentially causing device reboot. The vulnerability stems from improper memory management during DHCPv6 packet processing and only affects IPv6 traffic when unicast routing is enabled on the Bridge Domain.

MitigationDisable unicast routing on affected Bridge Domains as a workaround, or apply the Cisco software update addressing CVE-2018-0372. The vulnerability affects version 13.0(1k) specifically.

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:= 13.0\(1k\)

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. Confirm Cisco Nexus 9000 Series in ACI Mode
    Run 'show version' or 'show running-config' to identify the device model and confirm it is a Nexus 9000 Series Fabric Switches running in ACI mode
    Affected if Device is not a Nexus 9000 Series in ACI mode, then not affected by this specific CVE
  2. Verify installed software version
    Run 'show version' and look for version 13.0(1k) specifically. Compare your installed NX-OS version against the affected version 13.0(1k)
    Affected if The installed version is exactly 13.0(1k)
  3. Check if DHCPv6 is configured
    Run 'show running-config dhcpv6' or search for dhcpv6-related configuration in the running configuration to determine if DHCPv6 feature is in use
    Affected if DHCPv6 is not configured or not in use, the vulnerability is not reachable
  4. Confirm unicast routing is enabled on Bridge Domain
    Run 'show bridge-domain' or 'show running-config bridge-domain' to check the Bridge Domain configuration and determine if unicast routing is enabled for IPv6
    Affected if Unicast routing is NOT enabled on the Bridge Domain, the attack vector is not present
  5. Verify IPv6 is enabled on the affected Bridge Domain
    Run 'show ip6 interface' or check the Bridge Domain IPv6 settings to confirm IPv6 traffic is enabled
    Affected if IPv6 is not enabled, the DHCPv6 packets cannot trigger the vulnerability

A Nexus 9000 Series switch in ACI mode running version 13.0(1k) with DHCPv6 configured, unicast routing enabled on a Bridge Domain, and IPv6 traffic enabled is affected by this vulnerability.

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

Disable unicast routing on affected Bridge Domains as a workaround, or apply the Cisco software update addressing CVE-2018-0372. The vulnerability affects version 13.0(1k) specifically.

Fix this in Nx Os Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,980
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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-2018-0372 in production — separate from our analysis above.

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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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