CVE-2022-48872 is a use-after-free vulnerability identified in the Linux kernel's fastrpc subsystem, specifically related to the management of map objects. The vulnerability arises from a race condition between threads when handling references to map structures. In the vulnerable code, after calling fastrpc_map_get(), the system attempts to acquire a lock on the map in fastrpc_free_map(). However, before the lock is obtained, another thread may call fastrpc_map_lookup() and obtain a reference to a map that is in the process of being deleted. This leads to a use-after-free condition where a reference count is incremented on a map object that is already freed or about to be freed, causing potential memory corruption or kernel instability. The fix involves rewriting fastrpc_map_get() to only increase the reference count if it is non-zero, thereby preventing references to maps that are being deleted. This change propagates to callers to allow them to detect if a map is about to be deleted and avoid unsafe references. The vulnerability is rooted in improper synchronization and reference counting in the fastrpc driver, which is used for fast remote procedure calls on certain ARM-based platforms. The issue was detected through kernel warnings about refcount saturation and use-after-free errors. No known exploits are reported in the wild as of now. The affected versions are specific Linux kernel commits identified by their hashes, indicating this is a recent and targeted fix. This vulnerability is significant because it affects core kernel memory management and can lead to system crashes or potential escalation of privileges if exploited by a malicious actor able to trigger the race condition.

For European organizations, the impact of CVE-2022-48872 depends largely on the deployment of Linux systems that utilize the fastrpc subsystem, which is primarily found in ARM-based devices such as embedded systems, IoT devices, and certain mobile or edge computing platforms. Organizations relying on Linux servers or desktops without this subsystem are less likely to be affected. However, sectors with extensive use of ARM-based Linux devices—such as telecommunications, automotive, industrial control systems, and smart infrastructure—could face risks of system instability, denial of service, or potentially privilege escalation if attackers manage to exploit the race condition. This could disrupt critical services, cause data loss, or enable lateral movement within networks. Given the kernel-level nature of the vulnerability, successful exploitation could compromise the confidentiality, integrity, and availability of affected systems. The lack of known exploits reduces immediate risk, but the complexity of the vulnerability means that skilled attackers could develop exploits over time. European organizations with supply chains or products incorporating affected ARM Linux kernels should prioritize patching to maintain operational security and compliance with cybersecurity regulations such as NIS2.

1. Apply the official Linux kernel patches that address CVE-2022-48872 as soon as they are available and tested in your environment. Monitor kernel updates from trusted sources and vendors. 2. Identify and inventory all ARM-based Linux devices in your infrastructure, especially those running kernels with the vulnerable fastrpc subsystem. 3. For embedded or IoT devices that cannot be easily patched, consider network segmentation and strict access controls to limit exposure and reduce attack surface. 4. Implement runtime monitoring for kernel warnings related to refcount saturation or use-after-free errors, which may indicate attempted exploitation or instability. 5. Engage with device vendors and suppliers to ensure they provide patched firmware or kernel updates addressing this vulnerability. 6. Conduct security testing and code review for custom or third-party kernel modules that interact with fastrpc to detect similar race conditions. 7. Maintain up-to-date incident response plans that include procedures for kernel-level vulnerabilities and potential exploitation scenarios. 8. Educate system administrators and security teams about the specific risks of kernel race conditions and the importance of timely patching in embedded Linux environments.