CVE-2024-42108 is a use-after-free vulnerability identified in the Linux kernel's network subsystem, specifically within the rswitch driver code. The vulnerability arises in the rswitch_poll() function, where the skb (socket buffer) pointer is freed prematurely by dev_kfree_skb_any() in the rswitch_tx_free() inline function. However, immediately after freeing, the code attempts to access skb->len to update network interface statistics. Since skb and gq->skbs[gq->dirty] point to the same memory, this results in a use-after-free condition. This flaw can be triggered by sending simple network packets such as ARP requests or ICMP echo requests, making it trivial to reproduce and potentially exploitable for causing kernel crashes or denial of service. The bug was detected using KFENCE, a kernel memory error detector, and causes a kernel splat (crash) every few packets. Although no known exploits are currently reported in the wild, the vulnerability affects Linux kernel versions identified by specific commit hashes, indicating it is present in recent kernel builds prior to the patch. The issue is critical because it involves kernel memory management errors that can destabilize the system and potentially be leveraged for privilege escalation or remote denial of service attacks if combined with other vulnerabilities.

For European organizations, the impact of CVE-2024-42108 can be significant, especially for those relying heavily on Linux-based infrastructure in networking roles, such as data centers, cloud providers, telecom operators, and enterprises using Linux servers for critical services. The vulnerability can lead to kernel crashes causing denial of service, disrupting network availability and business continuity. In environments where Linux is used as a network router, firewall, or switch (including virtualized network functions), exploitation could degrade network performance or cause outages. Although no direct remote code execution is confirmed, the instability introduced by use-after-free bugs in kernel space can be a stepping stone for attackers to escalate privileges or bypass security controls. This risk is heightened in multi-tenant cloud environments common in Europe, where a compromised VM or container could impact other tenants. Additionally, critical infrastructure sectors such as finance, healthcare, and government agencies using Linux systems could face operational disruptions or increased exposure to targeted attacks if this vulnerability is exploited.

To mitigate CVE-2024-42108, European organizations should prioritize applying the official Linux kernel patches that reorder instructions to access skb->len before freeing the skb, thereby eliminating the use-after-free condition. Kernel updates should be tested and deployed promptly across all affected systems, especially those handling network traffic or acting as network devices. Network administrators should monitor for unusual kernel crashes or splats that may indicate exploitation attempts. Employing kernel memory debugging tools like KFENCE in testing environments can help detect similar memory errors proactively. Organizations should also implement strict network segmentation and ingress filtering to limit exposure to unsolicited ARP or ICMP packets from untrusted sources. For critical systems, consider deploying intrusion detection systems capable of monitoring kernel-level anomalies. Finally, maintain up-to-date backups and incident response plans to quickly recover from potential denial of service events caused by exploitation.