CVE-2025-23147 is a vulnerability identified in the Linux kernel's I3C master driver, specifically related to the handling of In-Band Interrupts (IBI) from target devices. The I3C protocol is used for communication between a master controller and multiple target devices, often in embedded systems or hardware interfacing scenarios. The vulnerability arises because the I3C master driver may receive an IBI from a target device before that device has been fully probed and initialized by its driver. During normal operation, the I3C master scans and probes target devices, and the target device driver enables IBI by assigning a handler to the device's ibi field. However, due to asynchronous event timing, the master can receive an IBI before the target device driver has completed this setup, resulting in a NULL pointer dereference when the master calls i3c_master_queue_ibi(). This leads to the kernel attempting to read from unreadable memory, causing a kernel panic and system crash. The vulnerability is rooted in a missing NULL pointer check in the i3c_master_queue_ibi() function. The patch involves adding this check to ensure that the driver does not attempt to queue an IBI handler task if the device's ibi pointer is uninitialized, thereby preventing the kernel panic and improving system stability. This issue affects Linux kernel versions identified by the commit hash 3a379bbcea0af6280e1ca0d1edfcf4e68cde6ee0 and potentially other versions that have not yet incorporated this fix. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet.

For European organizations, the impact of this vulnerability depends largely on the deployment of Linux-based systems utilizing the I3C protocol, which is common in embedded devices, IoT hardware, and specialized industrial equipment. A kernel panic caused by this vulnerability results in a denial of service (DoS) condition, potentially disrupting critical services, manufacturing processes, or embedded system operations. Organizations relying on Linux servers or devices that incorporate I3C master drivers could experience unexpected system crashes, leading to operational downtime and potential data loss if systems are not properly backed up or if the crash interrupts critical transactions. While this vulnerability does not directly lead to privilege escalation or data breach, the availability impact can be significant in environments where uptime is critical, such as telecommunications infrastructure, industrial control systems, or healthcare devices. Additionally, repeated kernel panics could increase maintenance costs and reduce confidence in system reliability. Since no known exploits exist yet, the immediate risk is moderate, but the potential for attackers to develop exploits that trigger kernel panics remotely or via crafted device interactions remains a concern.

European organizations should prioritize updating their Linux kernel versions to include the patch that adds the NULL pointer check in i3c_master_queue_ibi(). This requires tracking kernel updates from trusted Linux distributions and applying them promptly, especially for systems that use I3C hardware interfaces. For embedded and IoT devices, vendors should be engaged to provide firmware updates incorporating this fix. Additionally, organizations should audit their device inventory to identify systems using I3C master drivers and assess their exposure. Implementing robust monitoring for kernel panics and system crashes can help detect exploitation attempts or instability caused by this vulnerability. In environments where patching is delayed, consider isolating affected devices or limiting access to reduce the risk of triggering the vulnerability. Finally, organizations should incorporate this vulnerability into their incident response plans and ensure backups and failover mechanisms are in place to mitigate downtime caused by potential kernel panics.