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Nx OsOperating system · Cisco

CVE-2018-0311

HIGH · 7.5 CVSS v3.0 Published 2018-06-21
Fix available
A fix is available. Upgrade to 1.1.4.179 / 2.0.1.153 or later.
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 Cisco Fabric Services component of Cisco FXOS Software and Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability exists because the affected software insufficiently validates Cisco Fabric Services packets 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 cause process crashes and result in a DoS condition on the device. This vulnerability affects 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: CSCvd69960, CSCve02463, CSCve04859, CSCve41530, CSCve41537, CSCve41541, CSCve41557.

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 the Cisco Fabric Services packet processing of Cisco FXOS and NX-OS software. The affected software insufficiently validates Cisco Fabric Services packets, allowing an unauthenticated remote attacker to send maliciously crafted packets that cause a buffer overflow, resulting in process crashes and denial of service.

MitigationApply Cisco security patches for the affected products (Firepower 4100/9300, Nexus 3000/3500/5500/5600/6000/7000/7700/9000 series, MDS 9000, UCS 6100/6200/6300). If patches are unavailable, restrict network access to management interfaces and disable Cisco Fabric Services on untrusted segments.

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:= 7.0\(0\)hsk\(0.357\)= 8.1\(0.2\)s0= 8.8\(0.1\)= 8.0\(1\)= 8.8\(3.5\)s0= 6.0\(2\)a8\(9\)= 7.0\(3\)i4\(7\)= 7.0\(3\)i6\(2\)< 7.3\(3\)n1\(1\)< 3.2\(b\)
Firepower Extensible Operating SystemOperating system
Affected:>= 1.1, < 1.1.4.179>= 2.0, < 2.0.1.153>= 2.1.1, < 2.1.1.86>= 2.2.1, < 2.2.1.70>= 2.2.2, < 2.2.2.17

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 the installed product and version
    Run 'show version' on the device CLI to obtain the NX-OS or FXOS version string
    Affected if The version matches one of the affected ranges: NX-OS = 7.0(0)hsk(0.357), = 8.1(0.2)s0, = 8.8(0.1), = 8.0(1), = 8.8(3.5)s0, = 6.0(2)a8(9), = 7.0(3)i4(7), = 7.0(3)i6(2), < 7.3(3)n1(1), < 3.2(b); FXOS >= 1.1 and < 1.1.4.179, >= 2.0 and < 2.0.1.153, >= 2.1.1 and < 2.1.1.86, >= 2.2.1 and < 2.2.1.70, >=
  2. Verify Cisco Fabric Services is configured
    Run 'show cfs status' or 'show running-config | include cfs' to check if Cisco Fabric Services is enabled on the device
    Affected if CFS is enabled or configured, making the device susceptible to malformed packet exploitation
  3. Check for recent process crashes
    Review 'show process log' or 'show system internal log' for crashes in the_cfs process or fabric services related processes
    Affected if Buffer overflow exploitation may have caused process crashes

Device is affected if it runs an affected NX-OS or FXOS version AND has Cisco Fabric Services enabled on the network segment where untrusted packets can be received

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 1.1.4.179 / 2.0.1.153 / 2.1.1.86 or later
Fixed in 1.1.4.1792.0.1.1532.1.1.86
Interim mitigation

Apply Cisco security patches for the affected products (Firepower 4100/9300, Nexus 3000/3500/5500/5600/6000/7000/7700/9000 series, MDS 9000, UCS 6100/6200/6300). If patches are unavailable, restrict network access to management interfaces and disable Cisco Fabric Services on untrusted segments.

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-2018-0311 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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