CVE-2021-47620 is a vulnerability identified in the Linux kernel's Bluetooth subsystem. The issue arises from improper bounds checking during the processing of Bluetooth advertising data reports. Specifically, the vulnerability is related to an out-of-bound read condition that occurs at the end of a loop iterating over the number of Bluetooth advertising reports (num_reports). The original code performed the out-of-bound read check only after advancing a pointer within the loop, which could lead to false positives in the system's journal logs and potentially cause memory corruption or information disclosure. The patch refactors this logic by moving the bounds check to the beginning of the loop iteration, ensuring that the pointer is validated before it is dereferenced or advanced. This change prevents the kernel from reading beyond the allocated buffer, mitigating the risk of memory safety issues such as buffer over-reads. Although no known exploits are reported in the wild, the vulnerability affects the Linux kernel's Bluetooth stack, which is widely used across many Linux distributions and embedded devices. The affected versions are identified by a specific commit hash, indicating that the issue is present in certain kernel builds prior to the patch. The vulnerability does not require user interaction but may require the attacker to be within Bluetooth range to send malicious advertising data. No CVSS score has been assigned yet, but the technical details and patch information confirm the vulnerability's existence and resolution.

For European organizations, the impact of CVE-2021-47620 could be significant, especially for those relying heavily on Linux-based systems with Bluetooth capabilities. This includes enterprises using Linux servers, workstations, IoT devices, and embedded systems in industrial control, healthcare, telecommunications, and public infrastructure. The vulnerability could allow an attacker in physical proximity to a target device to cause out-of-bound reads, potentially leading to information leakage or kernel memory corruption. While direct remote exploitation is limited by the need for Bluetooth proximity, the widespread use of Linux in critical infrastructure and enterprise environments means that successful exploitation could disrupt operations or be leveraged as part of a larger attack chain. The false positives in system logs caused by the original issue could also hinder incident detection and response efforts. Given the lack of known exploits, the immediate risk is moderate, but the potential for future exploitation exists, especially as attackers develop more sophisticated Bluetooth-based attack techniques. Organizations with Bluetooth-enabled Linux devices should consider this vulnerability seriously, particularly in environments where physical security is less controlled or where Bluetooth is used extensively for device communication.

To mitigate CVE-2021-47620, European organizations should: 1) Apply the latest Linux kernel patches that include the fix for this vulnerability as soon as they become available from their Linux distribution vendors or kernel maintainers. 2) Audit and inventory all Linux-based devices with Bluetooth capabilities to identify those running vulnerable kernel versions. 3) Where patching is not immediately feasible, consider disabling Bluetooth functionality on critical systems or limiting Bluetooth usage to trusted devices only. 4) Implement strict physical security controls to restrict unauthorized proximity access to Bluetooth-enabled devices, especially in sensitive environments. 5) Enhance monitoring of Bluetooth-related logs and network activity to detect anomalous advertising data or unusual Bluetooth traffic patterns that could indicate exploitation attempts. 6) Educate security teams about the potential risks of Bluetooth vulnerabilities and incorporate Bluetooth security into regular vulnerability management and penetration testing activities. 7) Collaborate with device vendors and Linux distribution maintainers to ensure timely updates and security advisories are received and acted upon.