CVE-2023-4459 is a vulnerability identified in the vmxnet3 network driver within Red Hat Enterprise Linux 8.2 Advanced Update Support. The issue is a NULL pointer dereference located in the vmxnet3_rq_cleanup function in the vmxnet3_drv.c source file, part of the Linux kernel's networking subsystem. This flaw occurs due to a missing sanity check during the cleanup process of the vmxnet3 driver, which handles network packet reception in virtualized environments using VMware's vmxnet3 virtual NIC. A local attacker with standard user privileges can trigger this flaw by causing the driver to dereference a NULL pointer, leading to a kernel crash and resulting in a denial of service (DoS) condition. The vulnerability does not require elevated privileges beyond normal user access, nor does it require user interaction, making it relatively easier to exploit in environments where local access is possible. The impact is limited to availability, as confidentiality and integrity are not compromised. No public exploits or active exploitation have been reported to date. The vulnerability has a CVSS v3.1 base score of 5.5, reflecting medium severity, with attack vector local, low attack complexity, privileges required low, no user interaction, and impact limited to availability. This vulnerability is particularly relevant for organizations running Red Hat Enterprise Linux 8.2 in virtualized VMware environments where the vmxnet3 driver is in use. The flaw underscores the importance of input validation and error handling in kernel drivers to prevent system crashes caused by malformed or unexpected conditions during driver cleanup routines.

For European organizations, the primary impact of CVE-2023-4459 is the potential for denial of service on systems running Red Hat Enterprise Linux 8.2 with the vmxnet3 driver. This can lead to temporary loss of network connectivity and system availability, which may disrupt critical services, especially in data centers and cloud environments relying on VMware virtualization. Since the vulnerability requires local access, the risk is higher in environments where multiple users have shell or application-level access to the system, such as shared hosting, multi-tenant cloud platforms, or development environments. The disruption could affect business continuity, cause downtime, and potentially impact compliance with service-level agreements (SLAs). However, the vulnerability does not allow privilege escalation, data leakage, or code execution, limiting the scope of damage to availability only. Organizations with high reliance on Red Hat Enterprise Linux 8.2 in virtualized infrastructures should consider this a moderate operational risk that requires timely remediation to avoid service interruptions.

To mitigate CVE-2023-4459, European organizations should: 1) Apply the latest security patches and kernel updates provided by Red Hat for Enterprise Linux 8.2 Advanced Update Support as soon as they become available. 2) Restrict local user access to trusted personnel only, minimizing the risk of exploitation by untrusted users. 3) Monitor system logs and kernel messages for signs of vmxnet3 driver crashes or unusual network driver behavior that could indicate attempted exploitation. 4) In virtualized environments, consider isolating critical workloads and limiting user privileges to reduce the attack surface. 5) Employ kernel hardening techniques and security modules (e.g., SELinux) to enforce strict access controls on kernel components. 6) Conduct regular vulnerability scans and penetration tests focusing on local privilege and denial of service vectors. 7) Maintain robust backup and recovery procedures to quickly restore affected systems in case of a DoS event. These steps go beyond generic advice by emphasizing proactive monitoring, access control, and environment-specific hardening tailored to the vmxnet3 driver context.