CVE-2021-47233 is a vulnerability identified in the Linux kernel, specifically within the regulator driver for the rt4801 device. The issue arises due to a NULL pointer dereference caused when the priv->enable_gpios pointer is NULL. This occurs because the function devm_gpiod_get_array_optional may return NULL if no GPIO (General Purpose Input/Output) was assigned to the device. When the kernel code does not properly check for this NULL return value before dereferencing, it leads to a NULL pointer dereference, which can cause the kernel to crash (kernel panic) or exhibit undefined behavior. This vulnerability is a form of denial-of-service (DoS) condition affecting the availability of the system. The affected Linux kernel versions are identified by specific commit hashes, indicating that the issue is present in certain recent versions of the kernel source code. The vulnerability was reserved in April 2024 and published in May 2024. There are no known exploits in the wild at this time, and no CVSS score has been assigned. The root cause is a lack of proper NULL pointer validation in the GPIO handling code within the regulator driver, which is a low-level hardware interface component of the Linux kernel. This vulnerability is relevant to systems running Linux kernels that include this driver and have the rt4801 regulator device configured without assigned GPIOs, which may be common in embedded or specialized hardware environments.

For European organizations, the impact of CVE-2021-47233 primarily concerns systems running Linux kernels with the affected regulator driver, especially in embedded systems, industrial control systems, IoT devices, or specialized hardware that utilize the rt4801 regulator. A successful exploitation would cause a kernel crash, resulting in denial of service. This could disrupt critical infrastructure, manufacturing processes, or services relying on affected devices. While this vulnerability does not appear to allow privilege escalation or data compromise directly, the loss of availability can have significant operational consequences. In sectors such as manufacturing, energy, transportation, and telecommunications, which often use embedded Linux systems, this could lead to downtime or degraded service. European organizations with large deployments of Linux-based embedded devices or custom hardware should be aware of this risk. However, the absence of known exploits and the requirement for specific hardware configurations limit the immediate widespread impact. Nonetheless, the vulnerability highlights the importance of robust kernel code quality and proper error handling in critical systems.

To mitigate CVE-2021-47233, European organizations should: 1) Apply the latest Linux kernel patches that address this NULL pointer dereference vulnerability as soon as they become available from trusted sources or vendor distributions. 2) Audit and verify the configuration of devices using the rt4801 regulator driver to ensure that GPIO assignments are correctly set and that no device is operating with unassigned GPIOs that could trigger this condition. 3) For embedded and specialized hardware, coordinate with hardware vendors to confirm firmware and kernel versions include the fix. 4) Implement robust monitoring and alerting for kernel panics or crashes on affected systems to detect potential exploitation attempts or instability early. 5) Where possible, isolate critical embedded devices from untrusted networks to reduce exposure. 6) Conduct thorough testing of kernel updates in staging environments before deployment to avoid unintended disruptions. These steps go beyond generic advice by focusing on hardware configuration validation, vendor coordination, and proactive monitoring tailored to the nature of this vulnerability.