CVE-2024-35945 is a vulnerability identified in the Linux kernel's PHY (physical layer) device driver subsystem, specifically within the interrupt service routine (ISR) handling code. The issue arises because the kernel code unconditionally sets the phydev->irq field without verifying whether a valid interrupt handler is present. This can lead to a null pointer dereference when the ISR attempts to invoke the handler, causing a nullptr exception. Such exceptions in kernel space can result in kernel crashes (kernel panic), leading to denial of service (DoS) conditions. The vulnerability is addressed by adding a check to confirm the presence of a valid interrupt handler before using the irq field, or alternatively falling back to polling mode to avoid dereferencing null pointers. This fix prevents the kernel from crashing due to invalid interrupt handling in the PHY device driver. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The vulnerability affects specific Linux kernel versions identified by commit hashes, indicating it is a recent issue resolved shortly after discovery. The PHY device drivers are critical for managing physical network interfaces, so this vulnerability impacts network-related kernel operations.

For European organizations, the impact of CVE-2024-35945 primarily involves potential denial of service through kernel crashes on Linux systems that utilize affected PHY device drivers. Since Linux is widely deployed across servers, network appliances, embedded devices, and IoT infrastructure in Europe, a successful exploitation could disrupt network connectivity and availability. This is particularly significant for enterprises relying on Linux-based network infrastructure, telecommunications providers, and critical infrastructure operators. While this vulnerability does not appear to allow privilege escalation or data compromise directly, the resulting system instability could interrupt business operations, degrade service availability, and increase operational costs due to downtime and recovery efforts. Organizations with high availability requirements or those operating in regulated sectors such as finance, healthcare, and energy should be especially vigilant. The absence of known exploits reduces immediate risk, but the vulnerability’s presence in kernel-level network drivers means it could be targeted in the future by attackers aiming to cause disruption.

To mitigate CVE-2024-35945, European organizations should promptly apply the Linux kernel patches that include the fix for this vulnerability. This involves updating to the latest stable kernel versions where the null pointer check and fallback to polling mode have been implemented. System administrators should verify that all network interface drivers, especially PHY device drivers, are updated and tested in their environments. Additionally, organizations should implement robust kernel crash monitoring and alerting to detect any unexpected kernel panics that might indicate exploitation attempts. Network segmentation and limiting exposure of critical Linux systems to untrusted networks can reduce attack surface. For embedded or IoT devices running Linux kernels, vendors and operators should coordinate firmware updates to incorporate the patch. Finally, maintaining comprehensive backups and recovery plans will help minimize downtime if a denial of service occurs.