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Aironet Access Point SoftwareApplication · Cisco

CVE-2021-1437

HIGH · 7.5 CVSS v3.1 Published 2021-03-24
Fix available
A fix is available. Upgrade to 8.10.142.0 / 17.3.3 or later.
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 FlexConnect Upgrade feature of Cisco Aironet Series Access Points Software could allow an unauthenticated, remote attacker to obtain confidential information from an affected device. This vulnerability is due to an unrestricted Trivial File Transfer Protocol (TFTP) configuration. An attacker could exploit this vulnerability by sending a specific TFTP request to an affected device. A successful exploit could allow the attacker to download any file from the filesystem of the affected access point (AP).

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

Unrestricted TFTP configuration in the FlexConnect Upgrade feature of Cisco Aironet Series Access Points allows unauthenticated remote attackers to download arbitrary files from the device filesystem by sending specific TFTP requests.

MitigationRestrict or disable TFTP access on affected access points. If TFTP is required for legitimate upgrades, implement IP allow-listing and ensure the TFTP server is not exposed to untrusted 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
Aironet Access Point SoftwareApplication
Affected:all versions
Catalyst 9800 FirmwareOperating system
Affected:>= 17.1, < 17.3.3
Wireless Lan Controller SoftwareApplication
Affected:>= 8.10.112.0, < 8.10.142.0

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
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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 version
    Log into the Cisco Wireless controller or access point CLI and run 'show version' or access the web UI to view the firmware/software version information.
    Affected if The device is a Cisco Aironet Access Point (any version), Cisco Catalyst 9800 (version 17.1 to 17.3.2), or Cisco Wireless LAN Controller (version 8.10.112.0 to 8.10.141.0).
  2. Confirm TFTP server is running on the device
    From the device CLI, run 'show tftp' or check the management interface settings for TFTP server status. In the web UI, navigate to Management > TFTP Server settings.
    Affected if TFTP server is enabled and running on the access point or controller.
  3. Check if FlexConnect Upgrade feature is configured
    From the CLI, run 'show flexconnect' or 'show flexconnect group summary' to see if FlexConnect is enabled. In the web UI, check Wireless > FlexConnect settings.
    Affected if FlexConnect is enabled and TFTP is permitted for upgrade operations.
  4. Verify TFTP access control restrictions
    Review the TFTP configuration by running 'show running-config | include tftp' or checking the TFTP server access list in the web UI under Management > TFTP Access Control.
    Affected if No IP allow-listing or access restrictions are configured on the TFTP server, or the TFTP server is accessible from any source IP.

The device is affected if it runs a vulnerable software version AND has TFTP enabled with unrestricted access, allowing any remote attacker to request arbitrary files from the device filesystem.

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 8.10.142.0 / 17.3.3 or later
Fixed in 8.10.142.017.3.3
Interim mitigation

Restrict or disable TFTP access on affected access points. If TFTP is required for legitimate upgrades, implement IP allow-listing and ensure the TFTP server is not exposed to untrusted networks.

Fix this in Aironet Access Point Software Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,480
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,968.

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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-2021-1437 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