CVE-2024-46702 is a vulnerability identified in the Linux kernel specifically related to the Thunderbolt networking driver. The issue arises during the process of discrete host router NVM (Non-Volatile Memory) firmware upgrades, which can trigger a hot-removal event on the PCIe (Peripheral Component Interconnect Express) side due to NVM firmware authentication. When such a hot-removal occurs, if there is another host connected with enabled paths, the system may hang while attempting to tear down these paths. This hang is caused by the Thunderbolt networking driver attempting to clean up the paths redundantly in the function tb_disconnect_xdomain_paths(), which waits for a domain lock that is already held or in a state that causes blocking. The root cause is that the paths have already been cleaned up in a prior function, tb_stop(), making the additional cleanup unnecessary and problematic. The vulnerability fix involves marking the XDomain (cross-domain connection) as unplugged when the parent router is removed, allowing tb_disconnect_xdomain_paths() to detect this state and exit early without attempting redundant cleanup. This correction prevents the system hang by avoiding deadlock conditions during path teardown in multi-host Thunderbolt networking configurations. The vulnerability affects Linux kernel versions identified by the commit hash 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and was published on September 13, 2024. There are no known exploits in the wild at this time, and no CVSS score has been assigned yet.

For European organizations, this vulnerability could lead to system instability or denial of service conditions on Linux systems utilizing Thunderbolt networking with multi-host configurations, especially in environments where discrete host router NVM firmware upgrades are performed. The hang caused by the vulnerability can disrupt critical services relying on Thunderbolt networking, potentially affecting data transfer, device communication, and operational continuity. Organizations using Linux servers or workstations with Thunderbolt interfaces in data centers, research labs, or industrial control systems could experience downtime or degraded performance. While the vulnerability does not appear to allow direct code execution or privilege escalation, the availability impact could be significant in high-availability or real-time environments. Given the widespread use of Linux in European IT infrastructure and the increasing adoption of Thunderbolt technology for high-speed connectivity, the vulnerability poses a moderate risk to operational reliability if unpatched. However, the absence of known exploits and the requirement for specific hardware and operational conditions limit the immediate threat level.

European organizations should prioritize updating their Linux kernel to the patched versions that include the fix for CVE-2024-46702. Specifically, kernel maintainers and system administrators should apply the commit identified by hash 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 or later versions that incorporate the fix. It is important to test the updated kernel in staging environments to ensure compatibility with existing Thunderbolt hardware and multi-host configurations. Additionally, organizations should review their firmware upgrade procedures for discrete host routers to minimize hot-removal events during NVM authentication, possibly scheduling upgrades during maintenance windows to reduce impact. Monitoring system logs for signs of hangs or deadlocks related to Thunderbolt networking can help detect attempts to exploit or trigger this vulnerability. For environments where immediate patching is not feasible, temporarily disabling Thunderbolt networking or limiting multi-host path configurations may reduce exposure. Collaboration with hardware vendors to ensure firmware compatibility and updates aligned with kernel patches is also recommended.