dbcve.org
Sd Wan FirmwareOperating system · Cisco

CVE-2020-3351

HIGH · 8.6 CVSS v3.1 Published 2020-07-16
Fix available
A fix is available. Upgrade to 17.2.7 / 18.3.0 or later.
See remediation →
95/100
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 Cisco SD-WAN Solution Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to improper validation of fields in Cisco SD-WAN peering messages that are encapsulated in UDP packets. An attacker could exploit this vulnerability by sending crafted UDP messages to the targeted system. A successful exploit could allow the attacker to cause services on the device to fail, resulting in a DoS condition that could impact the targeted device and other devices that depend on it.

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 SD-WAN Solution Software due to improper validation of fields in Cisco SD-WAN peering messages encapsulated in UDP packets. An unauthenticated remote attacker can send crafted UDP messages to cause services on the device to fail, resulting in a denial of service condition that impacts the targeted device and dependent devices.

MitigationApply the vendor patch or upgrade to a fixed version of Cisco SD-WAN Solution Software. As an interim measure, consider filtering or restricting unsolicited UDP traffic to SD-WAN devices at network boundaries.

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
Sd Wan FirmwareOperating system
Affected:< 17.2.7>= 17.2.8, < 18.3.0
Vedge Cloud RouterWeb browser
Affected:all versions
Vsmart ControllerApplication
Affected:all versions

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
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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 Cisco SD-WAN product and version
    Log into the device CLI and run 'show version' or 'show system information' to display the product name, model, and running software version
    Affected if The device is running Cisco SD-WAN Firmware outside the fixed versions (17.2.7, 18.3.0+), or is a Vedge Cloud Router or Vsmart Controller of any version
  2. Confirm the device is a Cisco SD-WAN component
    Verify the device is part of the SD-WAN deployment by checking 'show sdwan version' or reviewing the product name from the version output
    Affected if The device is not a Cisco SD-WAN product (the vulnerability only affects SD-WAN components)
  3. Check if UDP encapsulation is enabled for SD-WAN peering
    Run 'show sdwan control connections' or 'show interface' to verify if UDP-based peering tunnels are configured. Also check 'show running-config | include udp' to see if UDP encapsulation is present
    Affected if UDP peering encapsulation is actively configured and the device is processing UDP-encapsulated peering messages
  4. Verify the specific firmware version against the affected ranges
    Compare the installed firmware version from 'show version' against: < 17.2.7, >= 17.2.8 and < 18.3.0 for SD-WAN Firmware; all versions for Vedge Cloud Router and Vsmart Controller
    Affected if The version falls within the vulnerable ranges or the product is an affected Vedge/Vsmart variant

A user is affected if the device is a Cisco SD-WAN component (Vedge Cloud Router, Vsmart Controller, or SD-WAN Firmware) running a vulnerable version with UDP peering enabled.

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 17.2.7 / 18.3.0 or later
Fixed in 17.2.718.3.0
Interim mitigation

Apply the vendor patch or upgrade to a fixed version of Cisco SD-WAN Solution Software. As an interim measure, consider filtering or restricting unsolicited UDP traffic to SD-WAN devices at network boundaries.

Fix this in Sd Wan Firmware 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-2020-3351 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