CVE-2024-20291 in NX-OS
Summary
by MITRE • 02/29/2024
A vulnerability in the access control list (ACL) programming for port channel subinterfaces of Cisco Nexus 3000 and 9000 Series Switches in standalone NX-OS mode could allow an unauthenticated, remote attacker to send traffic that should be blocked through an affected device.
This vulnerability is due to incorrect hardware programming that occurs when configuration changes are made to port channel member ports. An attacker could exploit this vulnerability by attempting to send traffic through an affected device. A successful exploit could allow the attacker to access network resources that should be protected by an ACL that was applied on port channel subinterfaces.
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Analysis
by VulDB Data Team • 04/03/2024
The vulnerability identified as CVE-2024-20291 represents a critical access control flaw in Cisco Nexus 3000 and 9000 Series Switches operating in standalone NX-OS mode. This security weakness specifically targets the access control list programming implementation for port channel subinterfaces, creating a pathway for unauthorized network access that bypasses intended security measures. The flaw manifests when configuration modifications are applied to port channel member ports, resulting in improper hardware programming that undermines the device's ability to enforce network segmentation policies. This vulnerability impacts organizations relying on Cisco switches for network security enforcement, potentially exposing sensitive network resources to unauthorized access.
The technical root cause of this vulnerability stems from incorrect hardware programming that occurs during dynamic configuration changes to port channel member ports within the switch's forwarding plane. When administrators modify port channel configurations, the system fails to properly update the hardware-level access control list entries for subinterfaces, leading to a state where traffic filtering rules are either not applied or are applied inconsistently. This hardware-level programming error creates a persistent security gap that allows malicious actors to inject traffic that should be blocked by ACLs configured on port channel subinterfaces. The vulnerability specifically affects the interaction between the software configuration management and the underlying hardware forwarding tables, where the synchronization between these layers fails to maintain consistent access control policies.
From an operational perspective, this vulnerability presents a significant risk to network security infrastructure, as it allows unauthenticated remote attackers to bypass network segmentation controls that are fundamental to protecting sensitive resources. An attacker exploiting this vulnerability could gain access to network segments that should be protected by ACLs, potentially leading to unauthorized data access, lateral movement within the network, and compromise of critical systems. The remote nature of the attack vector means that adversaries do not require physical access or network credentials to exploit this weakness, making it particularly dangerous in environments where network security relies heavily on ACL-based filtering. The impact extends beyond simple traffic redirection, as it undermines the entire access control framework that organizations depend upon for network security.
Organizations affected by CVE-2024-20291 should prioritize immediate remediation through official Cisco software updates and patches that address the hardware programming synchronization issue in port channel subinterface ACL handling. Network administrators should conduct comprehensive vulnerability assessments to identify affected devices and verify the implementation of temporary mitigation strategies such as disabling port channels or implementing redundant access control measures. The vulnerability aligns with CWE-284 Access Control Issues and demonstrates characteristics consistent with ATT&CK technique T1071.001 Application Layer Protocol: Web Protocols, where network access control bypasses create opportunities for unauthorized data access. Security teams should also implement enhanced monitoring for unusual traffic patterns that might indicate exploitation attempts, particularly focusing on traffic flow through port channel subinterfaces that should be restricted by ACLs. Regular security audits of network device configurations are essential to prevent similar issues in other network infrastructure components and to maintain the integrity of network segmentation policies.