CVE-2023-1390 is a high-severity remote denial of service (DoS) vulnerability affecting the Linux kernel's Transparent Inter-Process Communication (TIPC) kernel module. The vulnerability arises from a flaw in the tipc_link_xmit() function, which handles the transmission of network packets (SKBs) within the TIPC module. Specifically, the function enters a while loop that encounters an unknown or unexpected state when attempting to parse SKBs that are not present in the transmission queue. This anomalous behavior can be triggered remotely by sending just two small UDP packets to a system that has a UDP bearer configured for TIPC. The result is an immediate spike in CPU utilization to 100%, effectively causing a denial of service condition by exhausting system resources and rendering the system unresponsive or severely degraded in performance. The vulnerability does not require any authentication or user interaction, and the attack vector is network-based, making it exploitable remotely with low complexity. It affects Linux kernel versions prior to 5.11-rc4, where the issue has been fixed. The vulnerability is classified under CWE-1050, which relates to infinite loops or excessive resource consumption due to improper input handling. Although no known exploits are currently reported in the wild, the ease of exploitation and the potential impact on availability make this a significant threat for affected systems.

For European organizations, the impact of CVE-2023-1390 can be substantial, particularly for those relying on Linux-based infrastructure with TIPC enabled and UDP bearers configured. The vulnerability can lead to complete denial of service, disrupting critical services, applications, or network communications that depend on the affected kernel module. This can affect data centers, cloud service providers, telecommunications infrastructure, and industrial control systems that utilize Linux kernels with TIPC for inter-process or inter-node communication. The sudden CPU spike can cause system outages, degrade performance, and potentially lead to cascading failures in dependent services. Given that no confidentiality or integrity impact is reported, the primary concern is availability, which is critical for operational continuity. Organizations in sectors such as finance, healthcare, manufacturing, and public services could face operational disruptions, financial losses, and reputational damage if exploited. Additionally, the vulnerability's remote and unauthenticated nature increases the risk of opportunistic attacks, especially in environments exposed to untrusted networks or the internet.

To mitigate CVE-2023-1390, European organizations should prioritize upgrading their Linux kernels to version 5.11-rc4 or later, where the vulnerability is patched. For systems where immediate patching is not feasible, administrators should consider disabling the TIPC kernel module if it is not required, thereby eliminating the attack surface. Network-level mitigations include restricting UDP traffic to trusted sources and implementing firewall rules to block unsolicited UDP packets targeting TIPC-related ports. Monitoring CPU utilization and network traffic for anomalies can help detect potential exploitation attempts early. Additionally, organizations should audit their systems to identify any use of TIPC with UDP bearers and assess exposure, especially on publicly accessible servers. Employing intrusion detection/prevention systems (IDS/IPS) with signatures or heuristics for anomalous UDP traffic patterns related to TIPC may provide additional defense. Finally, maintaining robust incident response plans to quickly address DoS incidents will reduce downtime and operational impact.