dbcve.org
5508 Wireless Controller FirmwareOperating system · Cisco

CVE-2020-3273

HIGH · 7.5 CVSS v3.1 Published 2020-04-15
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 802.11 Generic Advertisement Service (GAS) frame processing function of Cisco Wireless LAN Controller (WLC) Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS). The vulnerability is due to incomplete input validation of the 802.11 GAS frames that are processed by an affected device. An attacker could exploit this vulnerability by sending a crafted 802.11 GAS frame over the air to an access point (AP), and that frame would then be relayed to the affected WLC. Also, an attacker with Layer 3 connectivity to the WLC could exploit this vulnerability by sending a malicious 802.11 GAS payload in a Control and Provisioning of Wireless Access Points (CAPWAP) packet to the device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS.

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 WLC software's 802.11 GAS frame processing allows unauthenticated remote attackers to cause device reload (DoS). Attackers exploit incomplete input validation by sending crafted 802.11 GAS frames either via wireless (relayed through an AP) or directly via CAPWAP at Layer 3.

MitigationApply the Cisco software update for CVE-2020-3273. Until patched, restrict Layer 3 access to the WLC and consider disabling GAS if not operationally required.

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
5508 Wireless Controller FirmwareOperating system
Affected:= 8.5\(151.0\)= 8.10\(204.92\)
5520 Wireless Controller FirmwareOperating system
Affected:= 8.5\(151.0\)= 8.10\(204.92\)

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 the WLC model
    Log into the WLC CLI and run 'show inventory' or check the controller physically/labels to confirm it is a Cisco 5508 or 5520 Wireless Controller
    Affected if The device is NOT a Cisco 5508 or 5520 WLC (this CVE only affects those specific models)
  2. Check the firmware version
    Log into the WLC CLI and run 'show version' to display the installed firmware version
    Affected if The firmware version matches or is earlier than 8.5(151.0) or 8.10(204.92)
  3. Verify 802.11 radio is enabled
    Log into the WLC CLI and run 'show 802.11a' or 'show 802.11b' to check if 802.11a or 802.11b/g radios are enabled
    Affected if 802.11a or 802.11b/g is enabled - GAS frames are processed when Wi-Fi radios are active
  4. Check CAPWAP allowed interfaces
    Log into the WLC CLI and run 'show capwap allow' to see if CAPWAP is permitted on any interface
    Affected if CAPWAP is enabled and allows Layer 3 connectivity (attackers can send crafted frames directly via CAPWAP at L3)
  5. Check management interface accessibility
    From an external host, attempt to reach the WLC management IP on port 5247 (CAPWAP) or verify if the management interface is exposed to untrusted networks
    Affected if The WLC management interface (or CAPWAP port 5247) is reachable from untrusted/anonymous networks

You are affected if you run a Cisco 5508 or 5520 WLC with firmware version 8.5(151.0), 8.10(204.92), or earlier in those release trains, and you have 802.11 radios enabled with any Layer 3 accessibility to the controller.

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 software update for CVE-2020-3273. Until patched, restrict Layer 3 access to the WLC and consider disabling GAS if not operationally required.

Fix this in 5508 Wireless Controller Firmware Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,580
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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-2020-3273 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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