CVE-2021-47360 is a vulnerability identified in the Linux kernel related to the binder driver, which is a core component used primarily for inter-process communication (IPC) in Android and other Linux-based systems. The issue arises during the BC_FREE_BUFFER processing phase, where the cleanup of BINDER_TYPE_FDA objects may close one or more file descriptors (fds). The closing of these fds is deferred and completed using the task work mechanism, which requires the thread to return to userspace for the file objects to be properly dereferenced and closed. If the thread does not return to userspace, the close operations may never complete, potentially causing hung processes. This can lead to resource leaks and system instability. The fix implemented forces the binder thread back to userspace if an fd is closed during BC_FREE_BUFFER handling, ensuring proper cleanup and preventing the hang condition. This vulnerability affects multiple versions of the Linux kernel as indicated by the affected commit hashes, and while it does not have known exploits in the wild, it poses a risk to system reliability and availability if left unpatched.

For European organizations, this vulnerability primarily threatens system stability and availability. Since the binder driver is heavily used in Android devices and some Linux-based embedded systems, organizations relying on such devices for operations, mobile workforce, or IoT infrastructure could experience hung processes or degraded performance, potentially disrupting business operations. Critical infrastructure or industrial control systems running Linux kernels with this vulnerability could face operational interruptions. Although this vulnerability does not directly lead to privilege escalation or data breaches, the denial-of-service-like effect from hung processes could impact service availability, especially in environments with high concurrency or real-time processing requirements. The lack of known exploits reduces immediate risk, but unpatched systems remain vulnerable to potential future exploitation or accidental triggering of the bug.

Organizations should prioritize applying the latest Linux kernel patches that address CVE-2021-47360. Specifically, updating to kernel versions that include the fix forcing binder threads back to userspace during BC_FREE_BUFFER handling is essential. For environments where immediate patching is challenging, monitoring system logs for binder-related errors or hung processes can help detect potential issues early. Additionally, implementing robust process monitoring and automated recovery mechanisms can mitigate the impact of hung processes. For Android device fleets, ensure that OEM updates or security patches are applied promptly. In embedded or IoT devices, coordinate with vendors to obtain patched firmware or kernel updates. Network segmentation and limiting exposure of vulnerable devices can reduce the risk of widespread disruption. Finally, maintain comprehensive backup and recovery plans to address any availability impacts caused by this vulnerability.