CVE-2019-1617 in NX-OS
Summary
by MITRE
A vulnerability in the Fibre Channel over Ethernet (FCoE) N-port Virtualization (NPV) protocol implementation in Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition. The vulnerability is due to an incorrect processing of FCoE packets when the fcoe-npv feature is uninstalled. An attacker could exploit this vulnerability by sending a stream of FCoE frames from an adjacent host to an affected device. An exploit could allow the attacker to cause packet amplification to occur, resulting in the saturation of interfaces and a DoS condition. Nexus 9000 Series Switches in Standalone NX-OS Mode are affected running software versions prior to 7.0(3)I7(5) and 9.2(2).
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Analysis
by VulDB Data Team • 07/31/2023
The vulnerability described in CVE-2019-1617 represents a critical denial of service weakness within Cisco NX-OS Software's implementation of the Fibre Channel over Ethernet N-port Virtualization protocol. This flaw specifically impacts Nexus 9000 Series Switches operating in standalone NX-OS mode and affects software versions prior to 7.0(3)I7(5) and 9.2(2). The vulnerability stems from improper handling of FCoE packets when the fcoe-npv feature has been removed from the system configuration, creating a condition where the device fails to properly process incoming traffic streams.
The technical exploitation mechanism involves an adjacent attacker sending a continuous stream of FCoE frames to the vulnerable device, leveraging the incorrect packet processing logic that exists when the fcoe-npv feature is no longer active. This improper handling results in packet amplification effects that can overwhelm network interfaces and trigger complete denial of service conditions. The vulnerability demonstrates a classic example of inadequate state management in network protocol implementations, where the system fails to properly transition from an active to a deactivated protocol state, leading to unexpected behavior during packet processing.
From an operational perspective, this vulnerability poses significant risk to network infrastructure availability as it allows an unauthenticated attacker with physical or logical access to adjacent network segments to disrupt critical network services. The attack requires minimal privileges and can be executed from a nearby network position, making it particularly dangerous in environments where network segmentation is not properly enforced. The packet amplification effect means that relatively small streams of malicious traffic can cause substantial network impact, potentially affecting multiple network services and creating cascading failures across interconnected systems.
Security professionals should recognize this vulnerability as a manifestation of CWE-20, "Improper Input Validation," and CWE-682, "Incorrect Calculation," within the context of network protocol implementations. The attack vector aligns with ATT&CK technique T1498, "Network Denial of Service," and T1562, "Impair Defenses," as it directly impacts system availability and network functionality. Organizations should prioritize immediate patching of affected systems to version 7.0(3)I7(5) or 9.2(2), depending on their hardware platform, and implement network segmentation controls to limit adjacent access to critical network infrastructure. Additionally, monitoring for unusual FCoE traffic patterns and implementing rate limiting mechanisms can help detect and mitigate exploitation attempts before they cause significant service disruption.