dbcve.org
Ios XeOperating system · Cisco

CVE-2025-20140

HIGH · 7.4 CVSS v3.1 Published 2025-05-07
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 the Wireless Network Control daemon (wncd) of Cisco IOS XE Software for Wireless LAN Controllers (WLCs) could allow an unauthenticated, adjacent wireless attacker to cause a denial of service (DoS) condition. This vulnerability is due to improper memory management. An attacker could exploit this vulnerability by sending a series of IPv6 network requests from an associated wireless IPv6 client to an affected device. To associate a client to a device, an attacker may first need to authenticate to the network, or associate freely in the case of a configured open network. A successful exploit could allow the attacker to cause the wncd process to consume available memory and eventually cause the device to stop responding, resulting in 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 memory management vulnerability in the Wireless Network Control daemon (wncd) of Cisco IOS XE Software allows an adjacent attacker with an IPv6 wireless client to send malicious network requests that exhaust memory in the wncd process, causing device DoS.

MitigationApply the Cisco IOS XE software update for this vulnerability. Until patched, implement network access controls to restrict unauthorized client association and consider IPv6 traffic filtering on wireless networks.

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:= 16.4.1= 16.4.2= 16.4.3= 16.5.1= 16.5.1a= 16.5.1b= 16.5.2= 16.5.3= 16.6.1= 16.6.2= 16.6.3= 16.6.4

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 IOS XE version
    Run 'show version' or 'show version | include Version' to retrieve the installed Cisco IOS XE software version
    Affected if The version matches one of the affected versions: 16.4.1, 16.4.2, 16.4.3, 16.5.1, 16.5.1a, 16.5.1b, 16.5.2, 16.5.3, 16.6.1, 16.6.2, 16.6.3, or 16.6.4
  2. Confirm wireless network control daemon is running
    Check if the wncd process is active on the device using 'show process cpu history' or 'show process memory' and look for wncd in the output
    Affected if The wncd process is running and consuming elevated memory, indicating potential exploitation
  3. Verify wireless client support configuration
    Check wireless client association settings using 'show wireless client summary' to see active wireless clients
    Affected if IPv6 wireless clients are associated or allowed to connect to the device
  4. Check for IPv6 wireless client presence
    Run 'show wireless client detail' or equivalent command to inspect client protocol configurations
    Affected if IPv6 is enabled on wireless client associations or the wireless management interface

The device is affected if it runs Cisco IOS XE versions 16.4.1 through 16.6.4, has the wncd wireless daemon active, and allows IPv6 wireless client connections that could trigger the memory exhaustion condition.

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 IOS XE software update for this vulnerability. Until patched, implement network access controls to restrict unauthorized client association and consider IPv6 traffic filtering on wireless networks.

Fix this in Ios Xe Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing8.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,800
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Scan for this in your stack

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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-2025-20140 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