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Nx OsOperating system · Cisco

CVE-2020-3165

HIGH · 8.2 CVSS v3.1 Published 2020-02-26
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
91/100
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 implementation of Border Gateway Protocol (BGP) Message Digest 5 (MD5) authentication in Cisco NX-OS Software could allow an unauthenticated, remote attacker to bypass MD5 authentication and establish a BGP connection with the device. The vulnerability occurs because the BGP MD5 authentication is bypassed if the peer does not have MD5 authentication configured, the NX-OS device does have BGP MD5 authentication configured, and the NX-OS BGP virtual routing and forwarding (VRF) name is configured to be greater than 19 characters. An attacker could exploit this vulnerability by attempting to establish a BGP session with the NX-OS peer. A successful exploit could allow the attacker to establish a BGP session with the NX-OS device without MD5 authentication. The Cisco implementation of the BGP protocol accepts incoming BGP traffic only from explicitly configured peers. To exploit this vulnerability, an attacker must send the malicious packets over a TCP connection that appears to come from a trusted BGP peer. To do so, the attacker must obtain information about the BGP peers in the affected system’s trusted network.

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

In Cisco NX-OS, BGP MD5 authentication can be bypassed when the NX-OS device has BGP MD5 authentication configured but the peer does not, AND the NX-OS BGP VRF name exceeds 19 characters. An attacker with knowledge of trusted BGP peer IP addresses can exploit this to establish unauthenticated BGP sessions with the affected device.

MitigationEnsure all BGP peers are configured with MD5 authentication, avoid using VRF names longer than 19 characters, and apply Cisco-provided patches for NX-OS. Alternatively, implement additional network-level controls to prevent spoofing of trusted BGP peer IP addresses.

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:= 9.2\(1\)= 9.2\(2\)= 9.2\(3\)= 9.3\(1\)

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
Low
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N

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 software version
    Run 'show version' on the NX-OS CLI and note the installed software version
    Affected if The version matches 9.2(1), 9.2(2), 9.2(3), or 9.3(1)
  2. Verify BGP MD5 authentication is configured on the device
    Run 'show running-config | include bgp' and look for 'password' or 'md5' configuration under the BGP routing process
    Affected if BGP MD5 authentication is configured on the local NX-OS device
  3. Check BGP peer configurations for missing MD5 authentication
    Run 'show ip bgp neighbors' or inspect the BGP configuration to examine each peer section for 'password' or 'md5' keywords
    Affected if Any BGP peer is configured without MD5 authentication
  4. Inspect BGP VRF names for length
    Run 'show vrf' and 'show running-config vrf <name>' to list VRF names, then count characters in each VRF name used in BGP configuration
    Affected if Any BGP VRF name exceeds 19 characters in length

The device is affected if it runs an affected NX-OS version (9.2(1), 9.2(2), 9.2(3), or 9.3(1)) AND has BGP MD5 authentication configured locally while at least one peer lacks MD5 authentication AND uses a BGP VRF name longer than 19 characters.

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

Ensure all BGP peers are configured with MD5 authentication, avoid using VRF names longer than 19 characters, and apply Cisco-provided patches for NX-OS. Alternatively, implement additional network-level controls to prevent spoofing of trusted BGP peer IP addresses.

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-2020-3165 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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