CVE-2021-1591: Cisco Nexus 9500 Series Switches Access Control List Bypass Vulnerability

Published Aug 25, 2021

Updated

A vulnerability in the EtherChannel port subscription logic of Cisco Nexus 9500 Series Switches could allow an unauthenticated, remote attacker to bypass access control list (ACL) rules that are configured on an affected device. This vulnerability is due to oversubscription of resources that occurs when applying ACLs to port channel interfaces. An attacker could exploit this vulnerability by attempting to access network resources that are protected by the ACL. A successful exploit could allow the attacker to access network resources that would be protected by the ACL that was applied on the port channel interface.

Affected Software

7 affected components

cisco NX-OS=9.3\(4\)

cisco Nexus 9500 16-slot

cisco Nexus 9500 4-slot

cisco Nexus 9500 8-slot

cisco Nexus 9504

Cisco Nexus 9508

cisco Nexus 9516

Remediation

Patch Available

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-nexus-acl-vrvQYPVe

Event History

Aug 25, 2021

CVE Published

via MITRE·07:11 PM

Data Sourced

via MITRE·07:11 PM

DescriptionSeverityWeakness

Frequently Asked Questions

What is the vulnerability ID?

The vulnerability ID is CVE-2021-1591.

What is the severity of CVE-2021-1591?

The severity of CVE-2021-1591 is medium.

How does CVE-2021-1591 affect Cisco Nexus 9500 Series Switches?

CVE-2021-1591 allows an unauthenticated, remote attacker to bypass access control list (ACL) rules configured on affected Cisco Nexus 9500 Series Switches.

What is the cause of CVE-2021-1591?

CVE-2021-1591 is caused by oversubscription of resources in the EtherChannel port subscription logic of Cisco Nexus 9500 Series Switches.

Is there a fix for CVE-2021-1591?

Yes, Cisco has provided a fix for CVE-2021-1591. Please refer to the Cisco Security Advisory for more information.