CVE-2023-5366 in OpenvSwitch
Summary
by MITRE • 10/25/2023
A flaw was found in Open vSwitch that allows ICMPv6 Neighbor Advertisement packets between virtual machines to bypass OpenFlow rules. This issue may allow a local attacker to create specially crafted packets with a modified or spoofed target IP address field that can redirect ICMPv6 traffic to arbitrary IP addresses.
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Analysis
by VulDB Data Team • 06/10/2025
The vulnerability identified as CVE-2023-5366 represents a significant security flaw within Open vSwitch, a widely deployed virtual switch implementation that forms the backbone of many software-defined networking (SDN) environments and cloud infrastructures. This issue specifically targets the handling of ICMPv6 Neighbor Advertisement packets within virtualized network environments, creating a critical bypass mechanism that undermines the fundamental security controls implemented through OpenFlow rule sets. The flaw exists at the network protocol processing layer where virtual machines communicate through ICMPv6, which is essential for IPv6 network operations including address resolution and neighbor discovery processes. Organizations relying on Open vSwitch for network segmentation and traffic control face substantial risk as this vulnerability directly compromises the integrity of their virtual network security policies.
The technical root cause of this vulnerability lies in the improper validation and processing of ICMPv6 Neighbor Advertisement packets within the Open vSwitch forwarding pipeline. When virtual machines exchange these packets as part of normal IPv6 network operations, the switch fails to properly enforce OpenFlow rules that should govern traffic flow based on destination IP addresses and other packet attributes. This processing gap allows an attacker to craft specially modified ICMPv6 packets where the target IP address field has been deliberately altered or spoofed. The vulnerability manifests because the Open vSwitch implementation does not adequately validate the consistency between the packet's source and target addresses in the neighbor advertisement context, enabling malicious actors to manipulate network routing decisions through seemingly legitimate network protocol traffic. This flaw operates at the Layer 3 network protocol level and specifically affects IPv6 implementations where ICMPv6 is used for network discovery and address resolution functions.
The operational impact of CVE-2023-5366 extends far beyond simple network disruption, creating opportunities for sophisticated network-based attacks that can compromise virtual machine isolation and network security boundaries. A local attacker with access to the virtual network environment can exploit this vulnerability to redirect ICMPv6 traffic to arbitrary IP addresses, potentially enabling man-in-the-middle attacks, network reconnaissance, or even lateral movement within virtualized environments. The ability to manipulate neighbor advertisement packets effectively allows attackers to poison the IPv6 neighbor cache of virtual machines, redirecting traffic intended for legitimate network endpoints to attacker-controlled destinations. This capability directly violates fundamental security principles of network isolation and can lead to complete compromise of virtual network security policies, as OpenFlow rules designed to control traffic flow become ineffective against this specific class of packet manipulation. The impact is particularly severe in cloud environments and data centers where Open vSwitch is extensively deployed for virtual network segmentation and security enforcement.
Organizations affected by this vulnerability should implement immediate mitigations including updating to patched versions of Open vSwitch where available, implementing additional network monitoring to detect anomalous ICMPv6 traffic patterns, and reviewing existing OpenFlow rule sets for potential bypass scenarios. Network administrators should also consider implementing ingress and egress filtering policies that specifically target ICMPv6 neighbor advertisement packets to prevent unauthorized traffic redirection. The vulnerability aligns with CWE-284 Access Control Issues and can be categorized under ATT&CK technique T1046 Network Service Scanning, as it enables attackers to manipulate network services and routing behaviors. Security teams should also monitor for potential exploitation attempts through anomalous network traffic that might indicate ICMPv6 packet manipulation activities, as this vulnerability can be leveraged for advanced persistent threat operations where network-based reconnaissance and lateral movement are key objectives. The remediation process requires careful consideration of network topology changes and potential impact on legitimate network operations while ensuring complete mitigation of the vulnerability across all affected virtualized environments.