CVE-2022-49908 is a vulnerability identified in the Linux kernel's Bluetooth subsystem, specifically within the Logical Link Control and Adaptation Protocol (L2CAP) implementation. The issue is a memory leak occurring in the vhci_write function of the virtual HCI (Host Controller Interface) driver. The vulnerability was discovered through fuzzing with Syzkaller, which reported unreferenced memory objects indicating a leak. The root cause lies in the handling of ACL (Asynchronous Connection-Less) data packets by the HCI core. When processing fragmented L2CAP packets, if the initial fragment does not contain the L2CAP length field, the HCI core copies the socket buffer (skb) into the connection's receive buffer (conn->rx_skb) and completes processing without freeing the original skb, resulting in a memory leak. This leak occurs because the skb is not released after processing in the l2cap_recv_acldata() function. The patch for this vulnerability ensures that the skb is properly freed after handling this specific case, preventing the memory leak. The vulnerability affects Linux kernel versions identified by the commit hashes provided, and it is relevant to systems using Bluetooth functionality via the Linux kernel's virtual HCI driver. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet.

For European organizations, this vulnerability primarily impacts systems running vulnerable Linux kernel versions with Bluetooth enabled, especially those utilizing virtual HCI drivers or Bluetooth communication stacks. The memory leak could lead to gradual exhaustion of kernel memory resources, potentially causing system instability, degraded performance, or crashes over time. This is particularly critical for embedded systems, IoT devices, or industrial control systems relying on Linux with Bluetooth connectivity, which are common in sectors such as manufacturing, healthcare, and transportation. While the vulnerability does not directly allow code execution or privilege escalation, the denial of service resulting from resource exhaustion could disrupt critical services. Additionally, persistent memory leaks may increase the attack surface for further exploitation or facilitate lateral movement if combined with other vulnerabilities. The impact is more pronounced in environments with high Bluetooth traffic or where devices are expected to run continuously without frequent reboots, such as in telecommunications infrastructure or public transport systems.

To mitigate this vulnerability, organizations should apply the official Linux kernel patches that address CVE-2022-49908 as soon as they become available from their Linux distribution vendors. For systems where immediate patching is not feasible, disabling Bluetooth functionality or the virtual HCI driver can reduce exposure. Monitoring system logs and kernel memory usage for unusual patterns or increases in memory consumption related to Bluetooth operations can help detect exploitation attempts or the effects of the leak. Network segmentation and limiting Bluetooth device pairing to trusted devices can reduce the risk of exploitation. For embedded or IoT devices, firmware updates incorporating the patched kernel should be prioritized. Additionally, organizations should implement robust update management processes to ensure timely deployment of kernel security patches and maintain an inventory of devices running vulnerable kernel versions to prioritize remediation efforts.