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AUSCERT External Security Bulletin Redistribution
ESB-2024.0494
Cisco Small Business Series Switches Stacked Reload ACL
Bypass Vulnerability
25 January 2024
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco Small Business Series Switches
Publisher: Cisco Systems
Operating System: Cisco
Resolution: Patch/Upgrade
CVE Names: CVE-2024-20263
Original Bulletin:
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sb-bus-acl-bypass-5zn9hNJk
Comment: CVSS (Max): 5.8 CVE-2024-20263 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N)
CVSS Source: Cisco Systems
Calculator: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
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Cisco Small Business Series Switches Stacked Reload ACL Bypass Vulnerability
Priority: Medium
Advisory ID: cisco-sa-sb-bus-acl-bypass-5zn9hNJk
First Published: 2024 January 24 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCwf48882 CSCwh68993
CVE Names: CVE-2024-20263
Summary
o A vulnerability with the access control list (ACL) management within a
stacked switch configuration of Cisco Business 250 Series Smart Switches
and Business 350 Series Managed Switches could allow an unauthenticated,
remote attacker to bypass protection offered by a configured ACL on an
affected device.
This vulnerability is due to incorrect processing of ACLs on a stacked
configuration when either the primary or backup switches experience a full
stack reload or power cycle. An attacker could exploit this vulnerability
by sending crafted traffic through an affected device. A successful exploit
could allow the attacker to bypass configured ACLs, causing traffic to be
dropped or forwarded in an unexpected manner. The attacker does not have
control over the conditions that result in the device being in the
vulnerable state.
Note: In the vulnerable state, the ACL would be correctly applied on the
primary devices but could be incorrectly applied to the backup devices.
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-sb-bus-acl-bypass-5zn9hNJk
Affected Products
o Vulnerable Products
At the time of publication, this vulnerability affected the following Cisco
products if they were running a vulnerable release of Cisco Small Business
Firmware Software and were in a stacked configuration with ACLs configured:
250 Series Smart Switches
350 Series Managed Switches
350X Series Stackable Managed Switches
550X Series Stackable Managed Switches
Business 250 Series Smart Switches
Business 350 Series Managed Switches
For information on the stackable configuration of Business Switches, see
the Stacking Guidelines for Cisco Business Switches .
For information about which Cisco software releases were vulnerable at the
time of publication, see the Fixed Software section of this advisory. See
the Details section in the bug ID(s) at the top of this advisory for the
most complete and current information.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
Workarounds
o There are no workarounds that address this vulnerability.
This vulnerability can leave the ACL configuration in an undefined state on
the switch. As a mitigation, unbind the ACL from the non-working VLANs and
then bind the ACL again. This is not a permanent mitigation. It would need
to be reapplied if any switch stack member reloads or is power cycled.
For the specific steps for unbinding and rebinding non-working ACLs, see
the Cisco Business Switches 350 Series CLI Guide (pages 105 to 107) and the
Cisco Business 350 Series Switches Administration Guide (pages 325 to 326).
Contact the Cisco Technical Assistance Center (TAC) if further guidance is
needed.
While this mitigation has been deployed and was proven successful in a test
environment, customers should determine the applicability and effectiveness
in their own environment and under their own use conditions. Customers
should be aware that any workaround or mitigation that is implemented may
negatively impact the functionality or performance of their network based
on intrinsic customer deployment scenarios and limitations. Customers
should not deploy any workarounds or mitigations before first evaluating
the applicability to their own environment and any impact to such
environment.
Fixed Software
o 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.
Fixed Releases
At the time of publication, the release information in the following tables
was accurate. See the Details section in the bug ID(s) at the top of this
advisory for the most complete and current information.
Business 250 Series Smart Switches and Business 350 Series Managed Switches
Cisco Firmware Release First Fixed Release
3.4 and earlier 3.4.0.17
250 Series Smart Switches, 350 Series Managed Switches, 350X Series
Stackable Managed Switches, and 550X Series Stackable Managed Switches
Cisco Firmware Release First Fixed Release
2.5 and earlier 2.5.9.54
To download the firmware from the Software Center on Cisco.com, click
Browse all and choose Switches > LAN Switches - Small Business .
The Cisco Product Security Incident Response Team (PSIRT) validates only
the affected and fixed release information that is documented in this
advisory.
Exploitation and Public Announcements
o The Cisco 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
URL
o https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sb-bus-acl-bypass-5zn9hNJk
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2024-JAN-24 |
+----------+---------------------------+----------+--------+--------------+
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.
- --------------------------END INCLUDED TEXT--------------------
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