CVE-2021-47120 is a vulnerability identified in the Linux kernel's Human Interface Device (HID) subsystem, specifically related to the Apple Magic Mouse and Magic Trackpad 2 driver. The issue stems from a faulty sanity check introduced in commit 9d7b18668956, which was intended to add support for the Apple Magic Trackpad 2. The check incorrectly returned success instead of the expected error code (-ENODEV) when the device was not recognized. As a result, the remove callback function attempts to dereference a driver data pointer that was never properly initialized. This NULL pointer dereference occurs when the driver is unbound, such as during a USB disconnect event. The consequence is a potential kernel NULL pointer dereference, which can lead to a denial of service (system crash) or possibly other undefined behavior depending on the kernel's state and memory layout. Since this vulnerability is in the kernel's HID driver, it affects all Linux distributions using the vulnerable kernel versions containing the faulty commit. The vulnerability does not require user interaction beyond device connection and disconnection, and no authentication is needed to trigger it. No known exploits are reported in the wild at this time, and no CVSS score has been assigned yet. However, the issue has been publicly disclosed and patched in the Linux kernel source, indicating the importance of updating affected systems.

For European organizations, the impact of CVE-2021-47120 primarily involves potential denial of service conditions on Linux systems that use Apple Magic Mouse or Magic Trackpad 2 devices. This could disrupt operations on workstations, servers, or embedded systems running vulnerable Linux kernels, especially in environments where these input devices are common. Critical infrastructure or enterprise environments relying on Linux for workstation or server operations could experience system instability or crashes triggered by device disconnect events, potentially leading to downtime or loss of productivity. Although the vulnerability does not appear to allow privilege escalation or remote code execution, denial of service in sensitive environments can have cascading effects, including interruption of business processes, delayed response times, and increased operational costs. The lack of known exploits reduces immediate risk, but the public disclosure means attackers could develop exploits, increasing future risk. Organizations in Europe with Linux deployments in sectors such as finance, manufacturing, healthcare, and government should be aware of this vulnerability due to their reliance on stable Linux environments and the potential use of Apple peripherals.

To mitigate CVE-2021-47120, European organizations should: 1) Apply the latest Linux kernel patches that address this vulnerability as soon as they become available from their distribution vendors or directly from the Linux kernel source. 2) Audit and inventory Linux systems to identify those using vulnerable kernel versions and Apple Magic Mouse or Magic Trackpad 2 devices. 3) Where patching is delayed, consider temporarily disabling or avoiding the use of affected Apple HID devices on critical systems to prevent triggering the NULL pointer dereference. 4) Implement monitoring for kernel crashes or unusual system reboots that could indicate exploitation attempts. 5) Engage with hardware and software vendors to ensure compatibility and timely updates. 6) For environments with strict uptime requirements, test patches in staging environments before deployment to avoid unintended disruptions. 7) Educate IT staff about the vulnerability and the importance of prompt patching and device management.