CVE-2023-1668 is a high-severity vulnerability identified in Open vSwitch (OVS), an open-source multilayer virtual switch commonly used to provide network automation and virtual networking in cloud and data center environments. The flaw arises when OVS processes IP packets with the protocol field set to 0. In this scenario, OVS installs a datapath flow entry without correctly modifying the IP header as intended. This results in a datapath flow that matches all IP protocols (due to the nw_proto field being wildcarded) but contains an incorrect action. Consequently, other IP packets with protocols not equal to 0 that match this flow may be handled improperly. This behavior affects both kernel and userspace datapaths, potentially leading to incorrect packet forwarding or processing. The underlying weakness corresponds to CWE-670, which relates to the use of a risky function or method that can cause resource management issues or incorrect behavior. The vulnerability has a CVSS v3.1 base score of 8.2, indicating high severity, with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), low confidentiality impact (C:L), no integrity impact (I:N), and high availability impact (A:H). No known exploits have been reported in the wild as of the publication date (April 10, 2023), and no patches have been linked yet. The flaw could lead to denial of service or network disruption due to incorrect packet handling, affecting the availability of network services relying on OVS.

For European organizations, especially those operating large-scale cloud infrastructures, data centers, or virtualized network environments, this vulnerability poses a significant risk. Open vSwitch is widely deployed in OpenStack, Kubernetes networking, and other SDN (Software Defined Networking) solutions prevalent in Europe’s telecom, finance, and public sectors. The incorrect handling of IP packets could cause network outages or degraded performance, impacting critical services and business continuity. Since the vulnerability can be exploited remotely without authentication or user interaction, attackers could trigger network disruptions at scale. This could affect multi-tenant cloud environments, leading to denial of service conditions for multiple customers. Additionally, the wildcarding of IP protocols in the flow entry could cause unintended traffic to be mishandled, potentially exposing network segments to traffic leakage or misrouting, which may have secondary confidentiality or compliance implications. The high availability impact is particularly concerning for sectors requiring stringent uptime guarantees such as healthcare, finance, and government services in Europe.

1. Immediate mitigation should include monitoring and filtering network traffic to detect and block packets with IP protocol set to 0, which are uncommon and suspicious in most environments. 2. Network administrators should audit and restrict the use of Open vSwitch instances, especially those exposed to untrusted networks, and segment management interfaces to limit exposure. 3. Deploy strict flow rule validation and logging to detect anomalous flow installations that wildcard IP protocols unexpectedly. 4. Until an official patch is released, consider applying temporary workarounds such as disabling or limiting kernel datapath offloading features if feasible, or isolating vulnerable OVS instances behind additional firewall layers. 5. Engage with vendors and upstream projects to obtain patches or updates as soon as they become available and prioritize their deployment in production environments. 6. Conduct thorough testing of network functions post-patch to ensure that flow handling behaves correctly and no regressions occur. 7. Incorporate this vulnerability into incident response and threat hunting playbooks to quickly identify exploitation attempts.