CVE-2024-47738 is a vulnerability identified in the Linux kernel's wireless networking subsystem, specifically within the mac80211 component responsible for managing Wi-Fi operations. The issue relates to the handling of rate masks during offchannel transmission (TX). A rate mask is used to specify which transmission rates are supported or preferred. The vulnerability stems from the kernel incorrectly applying rate masks during offchannel transmissions, which are transmissions sent on a channel different from the one currently used for data communication, such as during scanning or background operations. This improper handling can lead to incorrect rate settings, causing warnings or errors such as 'no supported rate' being reported by syzbot, a kernel fuzzing tool. The root cause was traced back to a prior commit (9df66d5b9f45) that fixed the default HE (High Efficiency) transmit bitrate mask in the 2.4 GHz band but inadvertently introduced issues with offchannel transmissions. The fix involves ignoring incorrect rate mask settings during offchannel TX, similar to a previous fix for scanning transmissions, to prevent erroneous warnings and potential transmission failures. While the vulnerability does not appear to have a direct exploit in the wild, it affects the reliability and correctness of Wi-Fi transmissions on affected Linux kernel versions. The affected versions include several kernel commits identified by their hashes, indicating that multiple recent kernel versions are impacted. This vulnerability is technical and subtle, primarily affecting the wireless stack's internal handling of transmission rates rather than exposing a direct attack vector for remote exploitation. However, it could degrade wireless performance or stability in environments relying on offchannel transmissions, such as Wi-Fi scanning, background network management, or advanced wireless features.

For European organizations, the impact of CVE-2024-47738 is primarily related to the stability and reliability of wireless networking on Linux-based systems. Many enterprises, research institutions, and critical infrastructure operators in Europe use Linux servers, embedded devices, or network appliances that rely on Wi-Fi connectivity. This vulnerability could lead to intermittent wireless transmission failures or degraded performance, especially in environments with heavy Wi-Fi scanning or offchannel operations, such as dense urban areas, industrial IoT deployments, or public Wi-Fi hotspots. While it does not directly compromise confidentiality or integrity, degraded wireless performance can indirectly affect availability of network services, potentially disrupting business operations or critical communications. In sectors like manufacturing, healthcare, or transportation where Linux-based wireless devices are common, this could impact operational continuity. Additionally, organizations deploying advanced Wi-Fi features (e.g., HE MCS rates in 2.4 GHz bands) might experience more pronounced issues. Although no known exploits exist, the vulnerability could be leveraged by attackers to cause denial of service by triggering repeated transmission failures or forcing devices to fallback to less efficient rates, thereby reducing network throughput and increasing latency. This could be particularly impactful in environments with stringent availability requirements or where wireless connectivity is critical for remote monitoring and control.

To mitigate CVE-2024-47738, organizations should: 1) Apply the latest Linux kernel updates that include the patch fixing the offchannel TX rate mask handling. Since the vulnerability is tied to specific kernel commits, upgrading to a kernel version incorporating the fix is essential. 2) For environments where immediate kernel upgrades are not feasible, consider disabling or limiting offchannel transmissions or Wi-Fi scanning features temporarily to reduce exposure. 3) Monitor wireless network performance and logs for anomalies related to transmission errors or rate mask warnings, which could indicate the presence of the issue. 4) Test critical wireless-dependent applications and devices after patching to ensure stability and performance improvements. 5) Engage with Linux distribution vendors to confirm the inclusion of the fix in their kernel packages and prioritize deployment in production systems. 6) For embedded or IoT devices running custom Linux kernels, coordinate with device manufacturers or maintainers to obtain patched firmware versions. 7) Implement network segmentation and redundancy for critical wireless systems to minimize operational impact in case of degraded wireless performance. These steps go beyond generic advice by focusing on kernel patch management, operational monitoring, and vendor coordination specific to this vulnerability.