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Ios XeOperating system · Cisco

CVE-2022-20856

HIGH · 7.5 CVSS v3.1 Published 2022-09-30
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
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 processing of Control and Provisioning of Wireless Access Points (CAPWAP) Mobility messages in Cisco IOS XE Wireless Controller Software for the Catalyst 9000 Family could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to a logic error and improper management of resources related to the handling of CAPWAP Mobility messages. An attacker could exploit this vulnerability by sending crafted CAPWAP Mobility packets to an affected device. A successful exploit could allow the attacker to exhaust resources on the affected device. This would cause the device to reload, 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 logic error in Cisco IOS XE Wireless Controller Software for Catalyst 9000 Family causes improper resource management when processing CAPWAP Mobility messages. An unauthenticated remote attacker can send crafted CAPWAP Mobility packets to exhaust device resources, forcing the affected device to reload and causing denial of service.

MitigationApply the vendor-provided patch when available. Until then, consider network segmentation or ACLs to limit CAPWAP traffic to trusted sources, and monitor for unusual CAPWAP traffic patterns.

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:= 17.3.4c

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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 device model and software platform
    Run 'show version' or 'show inventory' to confirm the device is a Cisco Catalyst 9000 series switch and is running IOS XE software
    Affected if Device is not a Catalyst 9000 family member or does not run IOS XE
  2. Check IOS XE version
    Run 'show version' and locate the IOS XE software version number (for example, 'Version 17.3.4c')
    Affected if Version is exactly 17.3.4c
  3. Verify Wireless Controller feature is enabled
    Run 'show wireless mobility summary' or 'show running-config | include wireless' to check if wireless controller functionality is configured
    Affected if Wireless controller feature is enabled and CAPWAP is in use
  4. Confirm CAPWAP listen interfaces are accessible
    Run 'show wireless management interface' to identify which interface(s) accept CAPWAP connections, then determine if these are exposed to untrusted networks
    Affected if CAPWAP management interface is reachable from untrusted networks

If the device is a Catalyst 9000 running IOS XE version 17.3.4c with wireless controller enabled and CAPWAP interfaces exposed to untrusted networks, the environment is affected by this CVE.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor-provided patch when available. Until then, consider network segmentation or ACLs to limit CAPWAP traffic to trusted sources, and monitor for unusual CAPWAP traffic patterns.

Recommended fix Moderate confidence

Upgrade to the fixed IOS XE release for 17.3.x as specified in the Cisco security advisory for CVE-2022-20856 (check Cisco.com for the exact fixed version number)

  1. 1. Identify the current Cisco IOS XE Wireless Controller Software version running on the affected Catalyst 9000 Family device using 'show version' command
  2. 2. Access Cisco.com and navigate to the Cisco Security Advisories page for CVE-2022-20856 to obtain the specific fixed release information
  3. 3. Download the fixed IOS XE software version from Cisco's software download center
  4. 4. Upload the new software image to the device's flash storage
  5. 5. Configure boot system to point to the new image: 'boot system <flash:/new-image-name>'
  6. 6. Save configuration: 'write memory'
  7. 7. Reload the device to apply the new software: 'reload'
  8. 8. After reboot, verify the new version is running: 'show version'
Caveat Review Cisco release notes for any configuration or feature changes between 17.3.4c and the fixed version; some wireless features may behave differently

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Ios Xe Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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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-2022-20856 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