CVE-2024-42125 is a vulnerability identified in the Linux kernel specifically within the Realtek rtw89 WiFi driver firmware handling code. The issue arises when the system BIOS policy disables the use of the 6 GHz frequency band, which is relevant for WiFi 7 capable chips. In such cases, the 6 GHz sub-band (sband) pointer is set to NULL. The vulnerable code did not properly handle this NULL pointer scenario, leading to a potential kernel crash when the scan offload feature attempts to prohibit all 6 GHz channels without verifying the presence of a valid 6 GHz sband. This lack of NULL pointer handling can cause a denial of service (DoS) condition by crashing the kernel, impacting system stability and availability. The vulnerability affects Linux kernel versions identified by the commit hash 4ba24331c973eb1df0d3b67b0e3f8b7cde7765a7. No known exploits are currently reported in the wild, and no CVSS score has been assigned. The fix involves adding proper NULL pointer checks to prevent the kernel from crashing when the 6 GHz sband is unavailable due to BIOS policy restrictions.

For European organizations, this vulnerability primarily poses a risk of system instability and denial of service on Linux systems utilizing Realtek WiFi 7 chipsets with the rtw89 driver, especially where BIOS policies disable 6 GHz WiFi bands. Organizations relying on Linux servers, workstations, or embedded devices with affected WiFi hardware could experience unexpected kernel crashes, leading to service interruptions or downtime. This could impact critical infrastructure, enterprise networks, or industrial control systems that depend on stable wireless connectivity. Although the vulnerability does not appear to allow privilege escalation or remote code execution, the potential for DoS could disrupt business operations, particularly in environments where high availability is required. The absence of known exploits reduces immediate risk, but unpatched systems remain vulnerable to accidental or targeted triggering of the crash condition.

European organizations should promptly apply the Linux kernel patch that addresses this vulnerability by adding NULL pointer handling in the rtw89 WiFi driver firmware code. System administrators should verify that their Linux distributions have incorporated this fix or manually update the kernel to a patched version. Additionally, organizations should audit BIOS configurations to understand policies related to 6 GHz WiFi band usage and consider enabling the 6 GHz band if compatible and secure. Monitoring system logs for kernel crashes related to WiFi scanning can help detect attempts to trigger this vulnerability. For critical systems, implementing redundancy and failover mechanisms can mitigate the impact of potential DoS conditions. Finally, maintaining an up-to-date inventory of devices using Realtek WiFi 7 chipsets and the rtw89 driver will help prioritize patching efforts.