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Firepower Extensible Operating SystemOperating system · Cisco

CVE-2020-3172

HIGH · 8.8 CVSS v3.1 Published 2020-02-26
Fix available
A fix is available. Upgrade to 2.6.1.187 / 2.7.1.106 or later.
See remediation →
93/100
Remediation priority · Urgent
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 Discovery Protocol feature of Cisco FXOS Software and Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to execute arbitrary code as root or cause a denial of service (DoS) condition on an affected device. The vulnerability exists because of insufficiently validated Cisco Discovery Protocol packet headers. An attacker could exploit this vulnerability by sending a crafted Cisco Discovery Protocol packet to a Layer 2-adjacent affected device. A successful exploit could allow the attacker to cause a buffer overflow that could allow the attacker to execute arbitrary code as root or cause a DoS condition on the affected device. Note: Cisco Discovery Protocol is a Layer 2 protocol. To exploit this vulnerability, an attacker must be in the same broadcast domain as the affected device (Layer 2 adjacent). Note: This vulnerability is different from the following Cisco FXOS and NX-OS Software Cisco Discovery Protocol vulnerabilities that Cisco announced on Feb. 5, 2020: Cisco FXOS, IOS XR, and NX-OS Software Cisco Discovery Protocol Denial of Service Vulnerability and Cisco NX-OS Software Cisco Discovery Protocol Remote Code Execution Vulnerability.

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 Cisco Discovery Protocol (CDP) feature of Cisco FXOS and NX-OS software due to insufficiently validated CDP packet headers. An attacker on the same Layer 2 broadcast domain can send a crafted CDP packet causing overflow and enabling arbitrary code execution as root or denial of service.

MitigationApply Cisco security patches for FXOS/NX-OS. Alternatively, disable Cisco Discovery Protocol on affected devices if not required, or implement strict Layer 2 access controls to prevent unauthorized adjacent attackers.

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
Firepower Extensible Operating SystemOperating system
Affected:< 2.6.1.187>= 2.7, < 2.7.1.106
Ucs ManagerApplication
Affected:< 3.2\(3n\)>= 4.0, < 4.0\(4g\)
Nx OsOperating system
Affected:all versions= 5.2\(1\)sv5\(1.2\)= 7.3\(5\)n1\(1\)= 7.3\(0\)d1\(0.140\)= 7.3\(0\)d1\(0.146\)= 7.0\(3\)i3\(0.191\)= 13.2\(7.230\)= 14.2\(1i\)

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
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 Cisco software product
    Determine whether the device runs Cisco FXOS, Cisco UCS Manager, or Cisco NX-OS. Use 'show version' or check the system documentation.
    Affected if The device runs FXOS, UCS Manager, or NX-OS software.
  2. Determine the installed software version
    Run 'show version' on the device CLI to obtain the exact software version number. For FXOS, also run 'show version' from the FXOS chassis manager. For UCS Manager, run 'show version' from the UCS CLI.
    Affected if The installed version falls within the affected ranges: FXOS < 2.6.1.187 or >= 2.7.0 and < 2.7.1.106; UCS Manager < 3.2(3n) or >= 4.0(0) and < 4.0(4g); NX-OS any version or one of the specific versions listed (5.2(1)sv5(1.2), 7.3(5)n1(1), 7.3(0)d1(0.140), 7.3(0)d1(0.146), 7.0(3)i3(0.191), 13.2(7.230
  3. Verify if Cisco Discovery Protocol is enabled
    Run 'show cdp neighbor' or 'show cdp' from the device CLI. If output is returned showing neighbors or CDP is listed as enabled, the protocol is active.
    Affected if CDP is enabled and running on the device.
  4. Check CDP configuration status
    Run 'show running-config | include cdp' or 'show cdp interface' to see which interfaces have CDP enabled.
    Affected if CDP is enabled on any interface, particularly on accessible Layer 2 interfaces.

The device is affected if it runs FXOS, UCS Manager, or NX-OS within the affected version ranges AND has Cisco Discovery Protocol enabled on any interface.

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 2.6.1.187 / 2.7.1.106 / 3.2 or later
Fixed in 2.6.1.1872.7.1.1063.2
Interim mitigation

Apply Cisco security patches for FXOS/NX-OS. Alternatively, disable Cisco Discovery Protocol on affected devices if not required, or implement strict Layer 2 access controls to prevent unauthorized adjacent attackers.

Fix this in Firepower Extensible Operating System Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA3.0 h
27.0 hours of engineering $4,800
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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-2020-3172 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