CVE-2023-4387 is a use-after-free vulnerability identified in the vmxnet3 ethernet NIC driver within the Linux kernel, specifically impacting Red Hat Enterprise Linux 8. The flaw exists in the vmxnet3_rq_alloc_rx_buf function and manifests during the cleanup process in vmxnet3_rq_cleanup_all, where a double-free condition can occur. This double-free leads to memory corruption, which can cause the system to crash (denial of service) and potentially leak sensitive kernel memory information. The vulnerability requires local attacker privileges with low complexity and no user interaction, meaning an attacker with some access to the system could exploit it without needing to trick a user. The impact on confidentiality is significant due to the kernel information leak, and availability is also affected due to system crashes. The vulnerability is specific to VMware’s vmxnet3 driver, commonly used in virtualized environments running Red Hat Enterprise Linux 8. No public exploits have been reported yet, but the nature of the vulnerability makes it a concern for environments where local access might be obtained by malicious insiders or through compromised accounts. The CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H) indicates local attack vector, low attack complexity, low privileges required, no user interaction, unchanged scope, high confidentiality impact, no integrity impact, and high availability impact. This vulnerability highlights the risks in virtualized network drivers and the importance of kernel memory management security.

For European organizations, the impact of CVE-2023-4387 is primarily on systems running Red Hat Enterprise Linux 8 within VMware virtualized environments. The vulnerability allows local attackers to cause denial of service through system crashes and potentially leak sensitive kernel memory information, which could aid further attacks or data exfiltration. This can disrupt critical business operations, especially in sectors relying heavily on virtualization for cloud infrastructure, such as finance, telecommunications, and government. The confidentiality breach risk, while limited to kernel memory, could expose sensitive information about system internals or other virtual machines on the host, increasing the risk of lateral movement or privilege escalation. Organizations with multi-tenant environments or shared infrastructure are particularly vulnerable. The requirement for local access limits remote exploitation but does not eliminate risk from insider threats or compromised user accounts. The absence of known exploits in the wild reduces immediate risk but does not preclude future exploitation attempts. Overall, the vulnerability poses a high risk to availability and confidentiality in affected environments.

To mitigate CVE-2023-4387, European organizations should: 1) Apply the latest security patches and kernel updates provided by Red Hat for Enterprise Linux 8 as soon as they become available to address the double-free flaw in the vmxnet3 driver. 2) Restrict local user privileges rigorously, ensuring that only trusted users have access to systems running VMware virtualized RHEL 8 instances. 3) Implement strict access controls and monitoring for local login attempts and unusual system behavior indicative of exploitation attempts, such as unexpected crashes or kernel memory leaks. 4) Use security tools to monitor kernel logs and audit system calls related to the vmxnet3 driver to detect anomalies. 5) Consider isolating critical workloads or sensitive virtual machines to reduce the impact of potential kernel memory leaks. 6) Regularly review and update virtualization host security configurations to minimize attack surfaces. 7) Educate system administrators and security teams about this vulnerability and the importance of timely patching and monitoring. These steps go beyond generic advice by focusing on local privilege management, monitoring specific to the vmxnet3 driver, and virtualization environment hardening.