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Nx OsOperating system · Cisco

CVE-2018-0291

MEDIUM · 6.5 CVSS v3.0 Published 2018-06-20
Fix available
A fix is available. Upgrade to 2.2 / 3.2 or later.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable 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 Simple Network Management Protocol (SNMP) input packet processor of Cisco NX-OS Software could allow an authenticated, remote attacker to cause the SNMP application on an affected device to restart unexpectedly. The vulnerability is due to improper validation of SNMP protocol data units (PDUs) in SNMP packets. An attacker could exploit this vulnerability by sending a crafted SNMP packet to an affected device. A successful exploit could allow the attacker to cause the SNMP application to restart multiple times, leading to a system-level restart and a denial of service (DoS) condition. This vulnerability affects Nexus 2000 Series Switches, 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, UCS 6100 Series Fabric Interconnects, UCS 6200 Series Fabric Interconnects, UCS 6300 Series Fabric Interconnects. Cisco Bug IDs: CSCuw99630, CSCvg71290, CSCvj67977.

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 SNMP input packet processor of Cisco NX-OS Software allows an authenticated, remote attacker to cause unexpected SNMP application restarts by sending crafted SNMP packets with improperly validated PDUs. Repeated exploitation can trigger system-level restarts, resulting in denial of service across multiple Nexus switch series and UCS fabric interconnects.

MitigationApply Cisco's software patches for the identified bug IDs (CSCuw99630, CSCvg71290, CSCvj67977). As interim measures, disable SNMP if unused, restrict SNMP access to authorized management stations via ACLs, and consider SNMPv3 with authentication/encryption.

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:>= 6.0, < 7.3\(3\)n1\(1\)>= 6.2, < 8.1\(2\)< 7.0\(3\)i3>= 7.0\(3\)i4, < 7.0\(3\)i7\(1\)= 7.0< 2.2>= 2.5, < 3.2\(2b\)

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.0/AV:N/AC:L/PR:L/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 NX-OS version
    Run 'show version' on the Cisco NX-OS device and locate the 'system:' or 'NX-OS' version line
    Affected if The running version falls within any of these ranges: >= 6.0 and < 7.3(3)n1(1); >= 6.2 and < 8.1(2); < 7.0(3)i3; >= 7.0(3)i4 and < 7.0(3)i7(1); equals 7.0; < 2.2; >= 2.5 and < 3.2(2b)
  2. Verify SNMP is enabled
    Run 'show snmp' and check if SNMP is listed as enabled; also run 'show running-config | include snmp' to see SNMP configuration lines
    Affected if SNMP is enabled (any community string or user configured) on an affected version
  3. Check SNMP configuration details
    Run 'show snmp community' to view community strings, and 'show snmp user' to see SNMPv3 users
    Affected if SNMPv1/v2c with plaintext community strings or SNMPv3 with weak/no authentication is configured
  4. Identify SNMP access control
    Run 'show snmp acl' or check the running configuration for SNMP access lists attached to SNMP
    Affected if SNMP is accessible from non-management networks or has no ACL restrictions
  5. Review recent SNMP-related process restarts
    Run 'show system internal sysmgr service name snmp' to check SNMP process uptime; check 'show logging' for 'SNMP' or 'snmp' process restart messages
    Affected if Multiple unexpected SNMP process restarts are logged

The device is affected if it runs a vulnerable NX-OS version AND has SNMP enabled, regardless of SNMP ACLs, because the attacker only needs valid SNMP credentials to exploit the flaw.

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 2.2 / 3.2 / 7.0 or later
Fixed in 2.23.27.0
Interim mitigation

Apply Cisco's software patches for the identified bug IDs (CSCuw99630, CSCvg71290, CSCvj67977). As interim measures, disable SNMP if unused, restrict SNMP access to authorized management stations via ACLs, and consider SNMPv3 with authentication/encryption.

Fix this in Nx Os Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
30.0 hours of engineering $5,280
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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-2018-0291 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