-----BEGIN PGP SIGNED MESSAGE-----
AUSCERT External Security Bulletin Redistribution
Cisco IOS Access Points Software 802.11r Fast Transition
Denial of Service Vulnerability
18 July 2019
AusCERT Security Bulletin Summary
Product: Cisco IOS Access Points
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2019-1920
- --------------------------BEGIN INCLUDED TEXT--------------------
Cisco IOS Access Points Software 802.11r Fast Transition Denial of Service
Advisory ID: cisco-sa-20190717-aironet-dos
First Published: 2019 July 17 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds availableCisco Bug IDs: CSCvg95745
o A vulnerability in the 802.11r Fast Transition (FT) implementation for
Cisco IOS Access Points (APs) Software could allow an unauthenticated,
adjacent attacker to cause a denial of service (DoS) condition on an
The vulnerability is due to a lack of complete error handling condition for
client authentication requests sent to a targeted interface configured for
FT. An attacker could exploit this vulnerability by sending crafted
authentication request traffic to the targeted interface, causing the
device to restart unexpectedly.
Cisco has released software updates that address this vulnerability. There
are no workarounds that address this vulnerability.
This advisory is available at the following link:
o Vulnerable Products
This vulnerability affects Cisco Access Points that are running an affected
version of Cisco IOS Access Point Software configured for 802.11r FT.
Verification of 802.11r Fast Transition (FT) Configuration From the CLI:
From the CLI of the WLC for which the AP is associated, administrators may
issue the following show command to verify if the 802.11r FT feature is
configured on the device.
(Cisco Controller) > show wlan <wlan id>
802.11 Authentication................Open System
Static WEP Keys................Disabled
Wi-Fi Protected Access (WPA/WPA2).....Enabled
Verifying 802.11r Fast Transition (FT) Configuration From the (GUI) :
Step 1 : Choose the WLANs tab to open the WLANs window.
Step 2 : Click a WLAN ID .
Step 3 : Choose Security > Layer 2 to verify if the Fast Transition feature
is enabled or disabled on the device.
It is important to note the available adaptive option that exists within
the drop-down menu when configuring 802.11r Fast Transition for the
respective WLAN. This feature, if selected, could allow compatible 802.11r
Fast Transition wireless clients to utilize Fast Transition and become
vulnerable to the issue listed in the Summary section.
For information about which Cisco Access Point Software releases are
vulnerable, see the Fixed Software section of this advisory.
Products Confirmed Not Vulnerable
No other Cisco products are known to be affected by this vulnerability.
o There are no workarounds that address this vulnerability.
o Cisco has released free software updates that address the vulnerability
described in this advisory. Customers may only install and expect support
for software versions and feature sets for which they have purchased a
license. By installing, downloading, accessing, or otherwise using such
software upgrades, customers agree to follow the terms of the Cisco
Additionally, customers may only download software for which they have a
valid license, procured from Cisco directly, or through a Cisco authorized
reseller or partner. In most cases this will be a maintenance upgrade to
software that was previously purchased. Free security software updates do
not entitle customers to a new software license, additional software
feature sets, or major revision upgrades.
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
Customers Without Service Contracts
Customers who purchase directly from Cisco but do not hold a Cisco service
contract and customers who make purchases through third-party vendors but
are unsuccessful in obtaining fixed software through their point of sale
should obtain upgrades by contacting the Cisco TAC:
Customers should have the product serial number available and be prepared
to provide the URL of this advisory as evidence of entitlement to a free
In the following table, the left column lists major Cisco software
releases. The right column indicates whether a major release is affected by
the vulnerability described in this advisory and the first minor release
that includes the fix for this vulnerability.
Cisco IOS Access Points Major Software First Fixed Release for This
Prior to 8.0 184.108.40.206
8.8 Not vulnerable
8.9 Not vulnerable
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.
| Version | Description | Section | Status | Date |
| 1.0 | Initial public release. | - | Final | 2019-July-17 |
- --------------------------END INCLUDED TEXT--------------------
You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to firstname.lastname@example.org
and we will forward your request to the appropriate person.
NOTE: Third Party Rights
This security bulletin is provided as a service to AusCERT's members. As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.
NOTE: This is only the original release of the security bulletin. It may
not be updated when updates to the original are made. If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.
Contact information for the authors of the original document is included
in the Security Bulletin above. If you have any questions or need further
information, please contact them directly.
Previous advisories and external security bulletins can be retrieved from:
Australian Computer Emergency Response Team
The University of Queensland
Internet Email: email@example.com
Facsimile: (07) 3365 7031
Telephone: (07) 3365 4417 (International: +61 7 3365 4417)
AusCERT personnel answer during Queensland business hours
which are GMT+10:00 (AEST).
On call after hours for member emergencies only.
-----BEGIN PGP SIGNATURE-----
-----END PGP SIGNATURE-----