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Nx OsOperating system · Cisco

CVE-2018-0295

HIGH · 7.5 CVSS v3.0 Published 2018-06-20
Fix available
A fix is available. Upgrade to 7.0 / 7.3 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 Border Gateway Protocol (BGP) implementation of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition due to the device unexpectedly reloading. The vulnerability is due to incomplete input validation of the BGP update messages. An attacker could exploit this vulnerability by sending a crafted BGP update message to the targeted device. An exploit could allow the attacker to cause the switch to reload unexpectedly. The Cisco implementation of the BGP protocol only accepts incoming BGP traffic from explicitly defined peers. To exploit this vulnerability, an attacker must be able to send the malicious packets over a TCP connection that appears to come from a trusted BGP peer or inject malformed messages into the victim's BGP network. This would require obtaining information about the BGP peers in the affected system's trusted network. The vulnerability may be triggered when the router receives a malformed BGP message from a peer on an existing BGP session. At least one BGP neighbor session must be established for a router to be vulnerable. 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 Fabric Switches in Application Centric Infrastructure (ACI) mode, Nexus 9000 Series Switches in standalone NX-OS mode, Nexus 9500 R-Series Line Cards and Fabric Modules. Cisco Bug IDs: CSCve79599, CSCve87784, CSCve91371, CSCve91387.

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 Cisco NX-OS Software's Border Gateway Protocol (BGP) implementation allows an unauthenticated, remote attacker to cause a denial of service by sending crafted BGP update messages with incomplete input validation, causing the affected device to reload unexpectedly. Exploitation requires either spoofing traffic to appear from a trusted BGP peer or injecting malformed messages into an existing BGP session, which in turn requires knowledge of the trusted BGP peers.

MitigationApply Cisco-provided software updates for NX-OS to patch the vulnerability; meanwhile, implement BGP MD5 authentication and network-edge filtering to restrict BGP traffic to legitimate peers and prevent spoofed packets.

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\(3\)i4>= 7.0\(3\)i5, < 7.0\(3\)i6\(2\)= 7.0\(3\)i7= 7.0

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 NX-OS version
    Run 'show version' on the device CLI and locate the 'NX-OS' or 'system:' version line
    Affected if The version falls within any of these vulnerable 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); < 7.0(3)i4; >= 7.0(3)i5 and < 7.0(3)i6(2); equals 7.0(3)i7; equals 7.0(3)
  2. Verify BGP is enabled
    Run 'show bgp summary' or 'show ip bgp summary' to check for active BGP neighbors and an established session state
    Affected if BGP is running and has active neighbors (the vulnerability only affects devices with active BGP configuration)
  3. Check BGP MD5 authentication configuration
    Run 'show running-config | include bgp' and look for 'neighbor <ip> password' lines under the BGP configuration section, or use 'show bgp session' to view session details
    Affected if BGP is enabled but no MD5 password is configured for the BGP peers (lack of authentication makes exploitation easier)
  4. Inspect BGP peer configuration for trusted peers
    Review the BGP configuration with 'show running-config bgp' and note the configured neighbor IP addresses
    Affected if The device has BGP peers configured and the attacker could potentially spoof packets from or inject into these trusted peer sessions

A device is affected if it runs a vulnerable NX-OS version from the listed ranges AND has BGP enabled with active peers, particularly without MD5 authentication configured.

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 7.0 / 7.3 / 8.1 or later
Fixed in 7.07.38.1
Interim mitigation

Apply Cisco-provided software updates for NX-OS to patch the vulnerability; meanwhile, implement BGP MD5 authentication and network-edge filtering to restrict BGP traffic to legitimate peers and prevent spoofed packets.

Fix this in Nx Os Scoped from the published advisory
  • Consultation4.0 h
  • Implementation3.0 h
  • Testing4.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,300
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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-2018-0295 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