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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2019.3277 Cisco Nexus 9000 Series Fabric Switches ACI Mode Border Leaf Endpoint Learning Vulnerability 29 August 2019 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Nexus 9000 series switches Publisher: Cisco Systems Operating System: Cisco Impact/Access: Denial of Service -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2019-1977 Original Bulletin: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190828-nexus-aci-dos - --------------------------BEGIN INCLUDED TEXT-------------------- Cisco Nexus 9000 Series Fabric Switches ACI Mode Border Leaf Endpoint Learning Vulnerability Priority: Medium Advisory ID: cisco-sa-20190828-nexus-aci-dos First Published: 2019 August 28 16:00 GMT Version 1.0: Final Workarounds: No workarounds available Cisco Bug IDs: CSCvi11291 CVE-2019-1977 CWE-371 CVSS Score: 6.8 AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X Summary o A vulnerability within the Endpoint Learning feature of Cisco Nexus 9000 Series Switches running in Application Centric Infrastructure (ACI) mode could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an endpoint device in certain circumstances. The vulnerability is due to improper endpoint learning when packets are received on a specific port from outside the ACI fabric and destined to an endpoint located on a border leaf when Disable Remote Endpoint Learning has been enabled. This can result in a Remote (XR) entry being created for the impacted endpoint that will become stale if the endpoint migrates to a different port or leaf switch. This results in traffic not reaching the impacted endpoint until the Remote entry can be relearned by another mechanism. 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://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/ cisco-sa-20190828-nexus-aci-dos Affected Products o Vulnerable Products At the time of publication, this vulnerability affected Cisco Nexus 9000 Series Fabric Switches in ACI mode that were running Cisco NX-OS ACI Software releases earlier than 12.2(4M), 13.1(2u), or 13.2(1l). 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. Cisco has confirmed that this vulnerability does not affect the following Cisco products: Firepower 2100 Series Firepower 4100 Series Firepower 9300 Security Appliances MDS 9000 Series Multilayer Switches Nexus 1000 Virtual Edge for VMware vSphere Nexus 1000V Switch for Microsoft Hyper-V Nexus 1000V Switch for VMware vSphere Nexus 3000 Series Switches Nexus 3500 Platform Switches Nexus 3600 Platform Switches Nexus 5500 Platform Switches Nexus 5600 Platform Switches Nexus 6000 Series Switches Nexus 7000 Series Switches Nexus 7700 Series Switches Nexus 9000 Series Switches in standalone NX-OS mode Nexus 9500 R-Series Switching Platform UCS 6200 Series Fabric Interconnects UCS 6300 Series Fabric Interconnects UCS 6400 Series Fabric Interconnects Workarounds o There are no workarounds that address this vulnerability. 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 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 providers. Fixed Releases At the time of publication, Cisco NX-OS ACI Software releases 12.2(4M) and later, 13.1(2u) and later, and 13.2(1l) and later contained the fix for this vulnerability. See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information. Additional Resources For help determining the best Cisco NX-OS Software release for a Cisco Nexus Switch, administrators can refer to 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 and 3500 Series Switches Cisco Nexus 5000 Series Switches Cisco Nexus 5500 Platform Switches Cisco Nexus 6000 Series Switches Cisco Nexus 7000 Series Switches Cisco Nexus 9000 Series Switches Cisco Nexus 9000 Series ACI-Mode Switches For help determining the best Cisco NX-OS Software release for Cisco UCS, refer to the Recommended Releases documents in the release notes for the device. 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. URL o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/ cisco-sa-20190828-nexus-aci-dos Revision History o +---------+--------------------------+---------+--------+-----------------+ | Version | Description | Section | Status | Date | +---------+--------------------------+---------+--------+-----------------+ | 1.0 | Initial public release. | - | Final | 2019-August-28 | +---------+--------------------------+---------+--------+-----------------+ - --------------------------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 auscert@auscert.org.au 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: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au 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). 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