CVE-2024-46749 is a vulnerability identified in the Linux kernel specifically related to the Bluetooth subsystem's btnxpuart driver. The flaw involves a null pointer dereference in the btnxpuart_flush() function, which occurs when the driver attempts to free a socket buffer (skb) without verifying that the pointer is valid. This can happen during the flush and close operations, particularly when the firmware download process fails or is incomplete. The vulnerability manifests as a kernel crash (NULL pointer dereference) leading to an 'Oops' error, as evidenced by the detailed kernel log output showing an invalid memory access at address 0x80. The root cause is the absence of a check before freeing the rx->skb pointer, which can be NULL under certain failure conditions. This issue affects Linux kernel versions containing the vulnerable btnxpuart driver code prior to the patch. The btnxpuart driver is used in Bluetooth UART communication, often on embedded or specialized hardware platforms such as the FSL i.MX8MM EVK board referenced in the logs. Exploitation of this vulnerability can cause a denial of service (DoS) by crashing the kernel, leading to system instability or reboot. There is no indication that this vulnerability allows privilege escalation or arbitrary code execution. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The patch involves adding a null check before freeing the skb to prevent the kernel crash.

For European organizations, the primary impact of CVE-2024-46749 is the potential for denial of service on Linux systems utilizing the vulnerable Bluetooth btnxpuart driver. This is particularly relevant for organizations relying on embedded Linux devices or industrial systems that incorporate Bluetooth communication via UART interfaces, such as IoT devices, industrial control systems, or specialized hardware platforms. A kernel crash can disrupt critical operations, cause system downtime, and require manual intervention to restore service. While this vulnerability does not appear to allow remote code execution or data compromise, the availability impact could be significant in environments where uptime is critical, such as manufacturing, healthcare, or telecommunications. Additionally, the vulnerability may affect Linux-based development boards or embedded devices used in research and development within European tech sectors. Since the vulnerability requires the driver to be active and the firmware download process to fail or be incomplete, exploitation may be limited to specific operational scenarios, reducing the overall attack surface. However, unpatched systems remain at risk of unexpected crashes, which could be exploited by an attacker with local access or through crafted Bluetooth firmware updates.

European organizations should take the following specific mitigation steps: 1) Identify and inventory Linux systems and embedded devices using the btnxpuart Bluetooth driver, especially those running kernel versions prior to the patch date. 2) Apply the official Linux kernel patch that adds the null pointer check in btnxpuart_flush() as soon as it becomes available from trusted sources or Linux distribution maintainers. 3) For embedded devices or custom Linux builds, rebuild the kernel with the patched driver version and redeploy to affected devices. 4) Monitor system logs for kernel Oops messages related to Bluetooth or btnxpuart to detect potential exploitation attempts or crashes. 5) Implement robust firmware update validation processes to prevent incomplete or failed firmware downloads that could trigger the vulnerability. 6) Restrict local access to vulnerable devices and limit Bluetooth connectivity to trusted devices only, reducing the risk of triggering the flaw. 7) In environments where uptime is critical, consider deploying redundant systems or failover mechanisms to mitigate the impact of potential kernel crashes. 8) Engage with hardware vendors to confirm whether their devices are affected and request updated firmware or kernel versions if applicable.