Headline
CVE-2023-20115: Cisco Security Advisory: Cisco Nexus 3000 and 9000 Series Switches SFTP Server File Access Vulnerability
A vulnerability in the SFTP server implementation for Cisco Nexus 3000 Series Switches and 9000 Series Switches in standalone NX-OS mode could allow an authenticated, remote attacker to download or overwrite files from the underlying operating system of an affected device. This vulnerability is due to a logic error when verifying the user role when an SFTP connection is opened to an affected device. An attacker could exploit this vulnerability by connecting and authenticating via SFTP as a valid, non-administrator user. A successful exploit could allow the attacker to read or overwrite files from the underlying operating system with the privileges of the authenticated user. There are workarounds that address this vulnerability.
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.
Cisco NX-OS Software
To help customers determine their exposure to vulnerabilities in Cisco NX-OS 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 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 search for vulnerabilities that affect a specific software release. To use the form, follow these steps:
- Choose which advisories the tool will search-only this advisory, only advisories with a Critical or High Security Impact Rating (SIR), or all advisories.
- Choose the appropriate software.
- Choose the appropriate platform.
- Enter a release number-for example, 7.0(3)I7(5) for Cisco Nexus 3000 Series Switches or 14.0(1h) for Cisco NX-OS Software in ACI mode.
- Click Check.
**Cisco Nexus 3000 and 9000 Series Switches SMUs**
Cisco has released the following SMUs to address this vulnerability. Customers can download the SMUs from the Software Center on Cisco.com.
Cisco NX-OS Software Release
Platform
SMU Name
9.3(11)
Nexus 3000 and 9000 Series Switches
nxos.CSCwe47138-n9k\_ALL-1.0.0-9.3.11.lib32\_n9000.rpm
10.2(5)
Nexus 3000 and 9000 Series Switches
nxos64-cs.CSCwe47138-1.0.0-10.2.5.lib32\_64\_n9000.rpm
nxos64-msll.CSCwe47138-1.0.0-10.2.5.lib32\_64\_n9000.rpm
For details about downloading and installing SMUs in Cisco NX-OS Software for Cisco Nexus 3000, 7000, and 9000 Series Switches, see the Performing Software Maintenance Upgrades section of the Cisco NX-OS system management configuration guides for Cisco Nexus 3000 Series Switches and Cisco Nexus 9000 Series Switches.
**Additional Resources**
For help determining the best Cisco NX-OS Software release for a Cisco Nexus Switch, see the following Recommended Releases documents. If a security advisory recommends a later release, Cisco recommends following the advisory guidance.
> Cisco MDS Series Switches
> Cisco Nexus 1000V for VMware Switch
> Cisco Nexus 3000 Series Switches
> Cisco Nexus 5500 Platform Switches
> Cisco Nexus 5600 Platform Switches
> Cisco Nexus 6000 Series Switches
> Cisco Nexus 7000 Series Switches
> Cisco Nexus 9000 Series Switches
> Cisco Nexus 9000 Series ACI-Mode Switches
To determine the best release for Cisco UCS Software, see the Recommended Releases documents in the release notes for the device.