CVE-2019-1964 in NX-OS
Summary
by MITRE
A vulnerability in the IPv6 traffic processing of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause an unexpected restart of the netstack process on an affected device. The vulnerability is due to improper validation of IPv6 traffic sent through an affected device. An attacker could exploit this vulnerability by sending a malformed IPv6 packet through an affected device. A successful exploit could allow the attacker to cause a denial of service (DoS) condition while the netstack process restarts. A sustained attack could lead to a reboot of the device.
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Analysis
by VulDB Data Team • 12/07/2023
The vulnerability identified as CVE-2019-1964 represents a critical flaw in Cisco NX-OS Software that specifically targets IPv6 traffic processing mechanisms within network infrastructure devices. This vulnerability exists within the netstack process which is responsible for handling network traffic operations and maintaining system stability. The flaw manifests when the system fails to properly validate incoming IPv6 packets, creating an exploitable condition that can be leveraged by remote attackers without requiring authentication credentials. The affected devices typically include Cisco Nexus series switches and routers that operate with NX-OS software, making this vulnerability particularly concerning for enterprise network infrastructures that rely heavily on these platforms.
The technical exploitation of this vulnerability occurs through the transmission of malformed IPv6 packets that bypass normal validation procedures implemented by the software. When the netstack process encounters these improperly formatted packets, it fails to handle them gracefully and instead triggers an unexpected restart of the critical network processing component. This behavior stems from inadequate input validation and error handling within the IPv6 processing modules of the NX-OS software implementation. The vulnerability specifically relates to how the system processes certain IPv6 header structures and payload data that do not conform to standard network protocols, causing memory corruption or state inconsistencies that force the process to terminate and restart.
From an operational impact perspective, this vulnerability creates a significant denial of service condition that can severely disrupt network operations and potentially lead to complete system outages. The immediate effect of a successful exploitation is the temporary unavailability of network services as the netstack process restarts, which can take several seconds to minutes depending on the device configuration and load conditions. Network administrators may experience intermittent connectivity issues, service disruptions, and potential cascading failures if multiple devices in a network are simultaneously affected. The sustained nature of attacks can lead to repeated restart cycles that may eventually cause the device to reboot completely, requiring manual intervention and potentially resulting in extended network downtime.
The exploitation of this vulnerability aligns with tactics described in the MITRE ATT&CK framework under the "Execution" and "Impact" phases, particularly targeting network infrastructure components to achieve service disruption. This vulnerability is categorized as a CWE-129 weakness related to improper validation of input boundaries, specifically manifesting in network protocol handling implementations. Organizations implementing Cisco NX-OS solutions should prioritize immediate patching of affected devices to prevent exploitation, while also implementing network segmentation and monitoring to detect anomalous IPv6 traffic patterns. Network administrators should consider deploying intrusion detection systems capable of identifying malformed IPv6 packets and establishing incident response procedures that account for potential denial of service conditions. The vulnerability demonstrates the importance of robust input validation in network protocol implementations and highlights the need for comprehensive security testing of network infrastructure software to prevent similar issues in future deployments.