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AUSCERT External Security Bulletin Redistribution
ESB-2024.1833
Cisco IOS XE Software for Wireless LAN Controllers Multicast DNS Denial of
Service Vulnerability
28 March 2024
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AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco IOS XE Software
Publisher: Cisco Systems
Operating System: Cisco
Resolution: Patch/Upgrade
CVE Names: CVE-2024-20303
Original Bulletin:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-wlc-mdns-dos-4hv6pBGf
Comment: CVSS (Max): 7.4 CVE-2024-20303 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H)
CVSS Source: Cisco Systems
Calculator: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
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Cisco IOS XE Software for Wireless LAN Controllers Multicast DNS Denial of
Service Vulnerability
Priority: High
Advisory ID: cisco-sa-wlc-mdns-dos-4hv6pBGf
First Published: 2024 March 27 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCwf53124
CVE Names: CVE-2024-20303
CWEs: CWE-459
Summary
o A vulnerability in the multicast DNS (mDNS) gateway feature of Cisco IOS XE
Software for Wireless LAN Controllers (WLCs) could allow an
unauthenticated, adjacent attacker to cause a denial of service (DoS)
condition.
This vulnerability is due to improper management of mDNS client entries. An
attacker could exploit this vulnerability by connecting to the wireless
network and sending a continuous stream of specific mDNS packets. A
successful exploit could allow the attacker to cause the wireless
controller to have high CPU utilization, which could lead to access points
(APs) losing their connection to the controller and result in a DoS
condition.
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:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-wlc-mdns-dos-4hv6pBGf
This advisory is part of the March 2024 release of the Cisco IOS and IOS XE
Software Security Advisory Bundled Publication. For a complete list of the
advisories and links to them, see Cisco Event Response: March 2024
Semiannual Cisco IOS and IOS XE Software Security Advisory Bundled
Publication .
Affected Products
o Vulnerable Products
This vulnerability affects the following Cisco products if they are running
a vulnerable release of Cisco IOS XE Software, have the mDNS gateway
feature enabled, and are managing APs in FlexConnect mode:
Catalyst 9800-CL Wireless Controllers for Cloud
Catalyst 9800 Embedded Wireless Controller for Catalyst 9300, 9400, and
9500 Series Switches
Catalyst 9800 Series Wireless Controllers
Embedded Wireless Controller on Catalyst APs
For information about which Cisco software releases are vulnerable, see the
Fixed Software section of this advisory.
Determine the Device Configuration
To determine if there are any APs in FlexConnect mode, connect to the
wireless controller and use the show ap status | i Flex CLI command.
The following example shows the output when this command is issued on a
wireless controller with an AP in FlexConnect mode:
C9800#show ap status | i Flex
my_ap_name Enabled FlexConnect ES
If there is no output, there are no APs in FlexConnect mode.
To determine whether the mDNS gateway feature is enabled, connect to the
wireless controller and use the show mdns-sd summary CLI command. If the
output of that command includes mDNS Gateway: Enabled , the mDNS gateway
feature is enabled, as shown in the following example :
C9800#show mdns-sd summary
mDNS Gateway: Enabled
Active Query: Enabled
Periodicity (in minutes): 30
Transport Type: Both IPv4 and IPv6
If the output of both commands is similar to the preceding examples, the
device is affected by this vulnerability.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
Cisco has confirmed that this vulnerability does not affect the following
Cisco products:
IOS Software
IOS XR Software
Meraki products
NX-OS Software
WLC AireOS Software
Workarounds
o There are no workarounds that address this vulnerability.
Fixed Software
o Cisco has released free software updates that address the vulnerability
described in this advisory. Customers with service contracts that entitle
them to regular software updates should obtain security fixes through their
usual update channels.
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 software license:
https://www.cisco.com/c/en/us/products/end-user-license-agreement.html
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.
The Cisco Support and Downloads page on Cisco.com provides information
about licensing and downloads. This page can also display customer device
support coverage for customers who use the My Devices tool.
When considering software upgrades , customers are advised to regularly
consult the advisories for Cisco products, which are available from the
Cisco Security Advisories 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
providers.
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: https://www.cisco.com/c
/en/us/support/web/tsd-cisco-worldwide-contacts.html
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
upgrade.
Cisco IOS and IOS XE Software
To help customers determine their exposure to vulnerabilities in Cisco IOS
and IOS XE Software, Cisco provides the Cisco Software Checker . This tool
identifies any Cisco security advisories that impact a specific software
release and the earliest release that fixes the vulnerabilities that are
described in each advisory ("First Fixed"). If applicable, the tool also
returns the earliest release that fixes all the vulnerabilities that are
described in all the advisories that the Software Checker identifies
("Combined First Fixed").
To use the tool, go to the Cisco Software Checker page and follow the
instructions. Alternatively, use the following form to determine whether a
release is affected by any Cisco Security Advisory. To use the form, follow
these steps:
1. Choose which advisories the tool will search-only this advisory, only
advisories with a Critical or High Security Impact Rating (SIR) , or
all advisories.
2. Enter a release number-for example, 15.9(3)M2 or 17.3.3.
3. Click Check .
[2 ] [ ] [Critical,High,Medium]
[Only this advisory ]
[ ] [Check]
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.
Source
o This vulnerability was found during the resolution of a Cisco TAC support
case.
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.
Subscribe to Cisco Security Notifications
o Subscribe
Related to This Advisory
o Cisco Event Response: March 2024 Semiannual Cisco IOS and IOS XE Software
Security Advisory Bundled Publication
URL
o https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-wlc-mdns-dos-4hv6pBGf
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2024-MAR-27 |
+----------+---------------------------+----------+--------+--------------+
Legal Disclaimer
o THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND
OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT
OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES
THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
A standalone copy or paraphrase of the text of this document that omits the
distribution URL is an uncontrolled copy and may lack important information
or contain factual errors. The information in this document is intended for
end users of Cisco products.
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