A vulnerability in the FlexConnect Upgrade feature of Cisco Aironet Series Access Points Software could allow an unauthenticated, remote attacker to obtain confidential information from an affected device.
This vulnerability is due to an unrestricted Trivial File Transfer Protocol (TFTP) configuration. An attacker could exploit this vulnerability by sending a specific TFTP request to an affected device. A successful exploit could allow the attacker to download any file from the filesystem of the affected access point (AP).
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:
This vulnerability affects the following Cisco products if they are running a vulnerable release of Cisco Aironet Series Access Points Software and are acting as the FlexConnect AP Upgrade Master:
- 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
- Catalyst IW 6300 APs
- Integrated AP on 1100 Integrated Services Routers
- 6300 Series Embedded Services APs (ESW6300)
For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.
Determine the Device Configuration
To determine whether a device is acting as the FlexConnect AP Upgrade Master, complete the following steps:
- Log in to the Wireless LAN Controller management web interface.
- Choose Wireless > FlexConnect Groups.
- Click a Group Name to access the group configuration.
- Click Image Upgrade.
- Verify the status of the FlexConnect AP Upgrade check box:
- If checked: Check which AP is configured as master from the AP Name list.
- If not checked: The FlexConnect AP Upgrade is not being used and the devices are not 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 any Cisco Access Point series that is not listed in the Vulnerable Products section of this advisory.
There are no workarounds that address this vulnerability.
However, customers can disable the FlexConnect AP Upgrade feature as a mitigation. While this will make the image transfer less efficient, it will prevent exploitation of this vulnerability.
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.
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 software license:
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 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.
The process to upgrade the APs requires administrators to upgrade the wireless controller that the APs are registered to.
Customers are advised to upgrade to an appropriate fixed software release as indicated in the following table(s). To ensure a complete upgrade solution, consider that this advisory is part of a collection that includes the following advisories:
- cisco-sa-aironet-info-disc-BfWqghj: Cisco Aironet Access Points FlexConnect Upgrade Information Disclosure Vulnerability
- cisco-sa-aironet-mdns-dos-E6KwYuMx: Cisco Aironet Access Points FlexConnect Multicast DNS Denial of Service Vulnerability
- cisco-sa-ap-privesc-wEVfp8Ud: Cisco Access Point Software Arbitrary Code Execution Vulnerability
Cisco Access Points Managed by Wireless LAN Controller or Mobility Express
Cisco Wireless LAN Controller Software Release First Fixed Release for This Vulnerability First Fixed Release for All Vulnerabilities Described in This Collection of Advisories Earlier than 22.214.171.124 Not vulnerable. 126.96.36.199 188.8.131.52 and later 184.108.40.206 220.127.116.11
Cisco Access Points Managed by Catalyst 9800 Wireless Controller or Embedded Wireless Controller on Catalyst Access Points (EWC)
Cisco Catalyst 9800 Wireless Controller Software Release First Fixed Release for This Vulnerability First Fixed Release for All Vulnerabilities Described in This Collection of Advisories Earlier than 17.1 Not vulnerable. 17.3.3 17.1 Migrate to a fixed release. 17.3.3 17.2 Migrate to a fixed release. 17.3.3 17.3 Migrate to a fixed release. 17.3.3 17.4 and later Not vulnerable. 17.5.1 (Mar 2021)
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.
This vulnerability was found during internal security testing.
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 2021-MAR-24
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