CVE-2024-43879 is a vulnerability identified in the Linux kernel's wireless networking subsystem, specifically within the cfg80211 component responsible for managing Wi-Fi configuration and operations. The issue arises from improper handling of a specific Resource Unit (RU) allocation mode, namely the 2x996 RU allocation, in the function cfg80211_calculate_bitrate_he(). This function calculates the bitrate for High-Efficiency (HE) Wi-Fi transmissions, which are part of the 802.11ax (Wi-Fi 6) standard. The vulnerability manifests as the function not recognizing or correctly processing the NL80211_RATE_INFO_HE_RU_ALLOC_2x996 allocation, leading to kernel warnings such as "invalid HE MCS: bw:6, ru:6" and CPU warnings logged at net/wireless/util.c. This indicates that the kernel is encountering unexpected or unsupported parameters during bitrate calculation, which could potentially lead to instability or denial of service conditions. The fix involves updating the function to handle the 2x996 RU allocation similarly to how it handles 160 MHz bandwidth allocations, thereby preventing the kernel warnings and ensuring proper operation. Although no known exploits are reported in the wild, the vulnerability affects Linux kernel versions containing the specified commit hashes, which are likely recent or development versions. Since cfg80211 is a core component for wireless networking on Linux, this vulnerability could impact a wide range of devices using Linux-based operating systems with Wi-Fi 6 support.

For European organizations, the impact of CVE-2024-43879 primarily concerns the reliability and stability of wireless networking infrastructure running on Linux systems. Many enterprises, research institutions, and service providers in Europe rely on Linux-based servers, network appliances, and embedded devices for critical networking functions. A failure or instability in the wireless stack could lead to intermittent connectivity issues or denial of service, disrupting business operations, communications, and access to cloud or internal resources. Although the vulnerability does not currently have known exploits, the kernel warnings and potential for unexpected behavior could be leveraged by attackers to cause service interruptions or to facilitate further attacks if combined with other vulnerabilities. Given the increasing adoption of Wi-Fi 6 technology across Europe, especially in urban and industrial environments, this vulnerability could affect a broad spectrum of devices including laptops, IoT devices, and wireless access points running Linux. The confidentiality and integrity impact is likely limited since the vulnerability relates to bitrate calculation and does not directly expose sensitive data or allow privilege escalation. However, availability could be impacted if the kernel warnings lead to crashes or degraded wireless performance.

European organizations should prioritize updating their Linux kernel versions to include the patch that properly handles the 2x996 RU allocation in cfg80211_calculate_bitrate_he(). Since the vulnerability is in the kernel wireless subsystem, applying vendor-supplied kernel updates or mainline kernel patches is the most effective mitigation. Organizations should audit their Linux systems to identify those running affected kernel versions, especially those with Wi-Fi 6 hardware or configurations. For embedded or specialized devices, coordination with hardware vendors or firmware providers may be necessary to obtain patched kernel versions. Network administrators should monitor kernel logs for the specific warning messages described to detect unpatched systems. Additionally, temporarily disabling Wi-Fi 6 features or restricting the use of 2x996 RU allocations, if configurable, could serve as a workaround until patches are applied. Implementing robust network segmentation and monitoring can help limit the impact of any potential exploitation attempts. Finally, organizations should maintain an inventory of Linux-based wireless infrastructure and ensure timely patch management processes are in place to address such kernel vulnerabilities promptly.