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             AUSCERT External Security Bulletin Redistribution

        Cisco Aironet series access points receive security updates
                                12 May 2020


        AusCERT Security Bulletin Summary

Product:           Aironet access points
Publisher:         Cisco Systems
Operating System:  Cisco
Impact/Access:     Root Compromise          -- Existing Account      
                   Denial of Service        -- Remote/Unauthenticated
                   Access Confidential Data -- Existing Account      
Resolution:        Patch/Upgrade
CVE Names:         CVE-2019-1835 CVE-2019-1834 CVE-2019-1829
                   CVE-2019-1826 CVE-2019-1654 

Original Bulletin: 

Comment: This bulletin contains five (5) Cisco Systems security advisories.

Revision History:  May   12 2020: Vendor released final update 1.1 to include a fix
                   April 18 2019: Initial Release

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Cisco Aironet Series Access Points Denial of Service Vulnerability

Priority:        Medium

Advisory ID:     cisco-sa-20190417-air-ap-dos

First Published: 2019 April 17 16:00 GMT

Last Updated:    2020 May 11 15:39 GMT

Version 1.1:     Final

Workarounds:     YesCisco Bug IDs:   CSCvj96316CSCvm97169CSCvq46817



CVSS Score:


    A vulnerability in the internal packet processing of Cisco Aironet Series
    Access Points (APs) could allow an unauthenticated, adjacent attacker to
    cause a denial of service (DoS) condition on an affected AP if the switch
    interface where the AP is connected has port security configured.

    The vulnerability exists because the AP forwards some malformed wireless
    client packets outside of the Control and Provisioning of Wireless Access
    Points (CAPWAP) tunnel. An attacker could exploit this vulnerability by
    sending crafted wireless packets to an affected AP. A successful exploit
    could allow the attacker to trigger a security violation on the adjacent
    switch port, which could result in a DoS condition.

    Note: Though the Common Vulnerability Scoring System (CVSS) score
    corresponds to a High Security Impact Rating (SIR), this vulnerability is
    considered Medium because a workaround is available and exploitation
    requires a specific switch configuration.

    There are workarounds that address this vulnerability.

    This advisory is available at the following link:

Affected Products

    Vulnerable Products

    This vulnerability affects the following Cisco products if they are running
    a vulnerable software release:

       Aironet 1540 Series APs
       Aironet 1560 Series APs
       Aironet 1800 Series APs
       Aironet 2800 Series APs
       Aironet 3800 Series APs
       Aironet 4800 APs
       Catalyst 9100 APs

    For information about affected software releases, consult the Cisco bug ID
    (s) at the top of this advisory.

    Products Confirmed Not Vulnerable

    Only products listed in the Vulnerable Products section of this advisory
    are known to be affected by this vulnerability.


  o This vulnerability is exploitable only if the switch port adjacent to the
    AP is configured with port security and set to shut down when a violation
    is detected. In that case, client traffic is not encapsulated in a CAPWAP
    tunnel, so the switch will learn additional MAC addresses on the switch
    interface where the AP is connected. Once the limit for MAC addresses is
    reached, a security violation is triggered.

    By default, port security is disabled. When it is enabled, shutdown is the
    default security violation mode.


  o Administrators can configure the switch interface with port security to
    learn only one MAC address (the switch learns the AP MAC address during AP
    bootup) and, in case of a security violation, to drop any new learned MAC
    addresses. Using the CLI, configure the security violation mode to either
    protect or restrict , as in the following example:

        # configuration terminal
        # interface interface_id
        # switchport port-security violation {protect | restrict}

    Note: CLI commands may vary slightly by switch model.

Fixed Software

  o For information about fixed software releases, consult the Cisco bug ID(s)
    at the top of this advisory.

    When considering software upgrades, customers are advised to regularly
    consult the advisories for Cisco products, which are available from the
    Cisco Security Advisories and Alerts page , to determine exposure and a
    complete upgrade solution.

    In all cases, customers should ensure that the devices to be upgraded
    contain sufficient memory and confirm that current hardware and software
    configurations will continue to be supported properly by the new release.
    If the information is not clear, customers are advised to contact the Cisco
    Technical Assistance Center (TAC) or their contracted maintenance

Exploitation and Public Announcements

  o The Cisco Product Security Incident Response Team (PSIRT) is not aware of
    any public announcements or malicious use of the vulnerability that is
    described in this advisory.


  o This vulnerability was found during the resolution of a Cisco TAC support

Cisco Security Vulnerability Policy

  o To learn about Cisco security vulnerability disclosure policies and
    publications, see the Security Vulnerability Policy . This document also
    contains instructions for obtaining fixed software and receiving security
    vulnerability information from Cisco.


  o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/

Revision History

  o +---------+---------------------------+------------+--------+-------------+
    | Version |        Description        |  Section   | Status |    Date     |
    |         | Added bug ID with a more  |            |        |             |
    |         | complete fix. Added       |            |        |             |
    |         | Aironet 4800 APs and      | Header,    |        |             |
    | 1.1     | Catalyst 9100 APs to      | Vulnerable | Final  | 2020-MAY-11 |
    |         | Affected Products due to  | Products   |        |             |
    |         | change in impacted        |            |        |             |
    |         | software versions.        |            |        |             |
    | 1.0     | Initial public release.   | -          | Final  | 2019-APR-17 |

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