CVE-2024-42094 is a vulnerability identified in the Linux kernel, specifically within the net/iucv subsystem. The issue arises from the explicit allocation of a cpumask variable on the stack when the kernel is configured with CONFIG_CPUMASK_OFFSTACK=y. In this configuration, allocating cpumask variables explicitly on the stack is discouraged because it can lead to potential stack overflow conditions. Stack overflows in kernel space can cause system instability, crashes, or potentially allow attackers to execute arbitrary code with kernel privileges if exploited. The recommended fix involves using the *cpumask_var API(s), which abstracts the allocation of cpumask variables in a configuration-neutral manner. This approach delegates the allocation strategy to the CONFIG_CPUMASK_OFFSTACK setting, ensuring safe memory allocation practices that prevent stack overflows. The vulnerability affects multiple versions of the Linux kernel identified by the same commit hash, indicating a specific code state before the patch. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. However, the vulnerability is significant due to its potential to cause kernel stack overflows, which are critical in terms of system security and stability.

For European organizations, the impact of CVE-2024-42094 could be substantial, particularly for those relying on Linux-based infrastructure in critical environments such as finance, telecommunications, government, and industrial control systems. A stack overflow in the kernel can lead to denial of service through system crashes or, in worst cases, privilege escalation if an attacker crafts an exploit. This could compromise confidentiality, integrity, and availability of systems. Given Linux's widespread use in servers, cloud environments, and embedded devices across Europe, unpatched systems could be vulnerable to targeted attacks or accidental crashes. The absence of known exploits reduces immediate risk, but the vulnerability's nature means that it could be leveraged by sophisticated threat actors. Organizations with high availability requirements or those operating critical infrastructure should prioritize remediation to avoid potential disruptions or security breaches.

European organizations should take the following specific mitigation steps: 1) Identify all Linux systems running kernel versions affected by this vulnerability, focusing on those compiled with CONFIG_CPUMASK_OFFSTACK=y. 2) Apply the official Linux kernel patches that replace explicit stack allocation of cpumask variables with the *cpumask_var API(s). If vendor-specific kernels are used (e.g., Red Hat, SUSE, Ubuntu), monitor vendor advisories and apply their security updates promptly. 3) For custom or embedded Linux systems, review kernel configuration and source code to ensure compliance with safe cpumask allocation practices. 4) Implement kernel integrity monitoring and system behavior anomaly detection to identify potential exploitation attempts or crashes related to this vulnerability. 5) Conduct thorough testing in staging environments before deploying patches to production to avoid unintended side effects. 6) Maintain up-to-date backups and incident response plans to mitigate impact in case of exploitation. 7) Educate system administrators and security teams about this vulnerability and the importance of kernel patching.