dbcve.org
Ios XeOperating system · Cisco

CVE-2020-3390

HIGH · 7.4 CVSS v3.1 Published 2020-09-24
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
79/100
Remediation priority · High
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 Simple Network Management Protocol (SNMP) trap generation for wireless clients of the Cisco IOS XE Wireless Controller Software for the Cisco Catalyst 9000 Family could allow an unauthenticated, adjacent attacker to cause the device to unexpectedly reload, causing a denial of service (DoS) condition on an affected device. The vulnerability is due to the lack of input validation of the information used to generate an SNMP trap in relation to a wireless client connection. An attacker could exploit this vulnerability by sending an 802.1x packet with crafted parameters during the wireless authentication setup phase of a connection. A successful exploit could allow the attacker to cause the device to reload, causing a DoS condition.

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 IOS XE Wireless Controller Software for Catalyst 9000 devices exists due to lack of input validation when generating SNMP traps for wireless client 802.1x authentication. An adjacent, unauthenticated attacker can send crafted 802.1x packets during the wireless authentication phase, causing the device to unexpectedly reload and create a denial of service condition.

MitigationApply the Cisco patch for CVE-2020-3390 when available from Cisco. Until patched, consider network segmentation to limit adjacent attacker access to the wireless network and 802.1x authentication infrastructure.

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
Ios XeOperating system
Affected:= 16.12.1

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

CVSS:3.1/AV:A/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 device model and software platform
    Run 'show version' or 'show inventory' to confirm the device is a Cisco Catalyst 9000 series switch running Cisco IOS XE software.
    Affected if Device is not a Catalyst 9000 series or does not run IOS XE.
  2. Check the IOS XE version
    Run 'show version' and locate the IOS XE version number in the output. Compare it to the affected version 16.12.1.
    Affected if The installed IOS XE version is exactly 16.12.1.
  3. Verify wireless controller feature is enabled
    Run 'show wireless controller' or 'show wireless management' to confirm the wireless controller functionality is active on the device.
    Affected if Wireless controller feature is not enabled.
  4. Confirm 802.1x authentication is configured
    Run 'show run | include dot1x' or 'show authentication session' to check if 802.1x authentication is configured for wireless clients.
    Affected if 802.1x authentication is not configured for wireless clients.
  5. Check SNMP configuration for wireless authentication traps
    Run 'show snmp trap' or 'show run | include snmp' to verify SNMP is configured and check if wireless authentication-related traps are enabled.
    Affected if SNMP is not configured or wireless authentication traps are not enabled.

The device is affected if it is a Catalyst 9000 running IOS XE version 16.12.1 with the wireless controller feature enabled, 802.1x authentication configured for wireless clients, and SNMP traps for wireless authentication are active.

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

Apply the Cisco patch for CVE-2020-3390 when available from Cisco. Until patched, consider network segmentation to limit adjacent attacker access to the wireless network and 802.1x authentication infrastructure.

Fix this in Ios Xe Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing5.0 h
  • Review / QA3.0 h
17.0 hours of engineering $2,970
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,752.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2020-3390 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2020-3390 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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