CVE-2024-26978 is a vulnerability identified in the Linux kernel's serial driver subsystem, specifically within the max310x driver responsible for interfacing with certain serial communication devices over I2C. The flaw arises during the instantiation of a max14830 device from userspace via the sysfs interface, where an invalid or null device type pointer is not properly checked before use. This leads to a NULL pointer dereference in the kernel space, causing the kernel to crash or become unstable. The error manifests when a user attempts to create a new I2C device entry by echoing the device type and address into the /sys/bus/i2c/devices/i2c-2/new_device file, triggering the max310x_i2c_probe function. Without validation of the device type, the kernel dereferences a NULL pointer, resulting in a kernel panic or oops, which is a denial-of-service condition. The patch involves adding a validity check for the device type pointer before proceeding with device instantiation, aborting the probe with a clear error message if invalid. This vulnerability is categorized under CWE-476 (NULL Pointer Dereference), which is a common programming error that can lead to system crashes and instability. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The affected Linux kernel versions include multiple commits identified by their hashes, indicating that the issue spans several recent kernel versions prior to the fix. The vulnerability requires local userspace interaction to instantiate the device, but does not require elevated privileges to trigger the kernel panic, assuming the user has write access to the sysfs interface for I2C devices. This flaw primarily impacts system stability and availability rather than confidentiality or integrity, as it causes denial of service through kernel crashes rather than unauthorized data access or modification.

For European organizations, the primary impact of CVE-2024-26978 is on system availability and reliability. Systems running affected Linux kernel versions with the max310x serial driver enabled and exposing the I2C sysfs interface are vulnerable to denial-of-service conditions triggered by local userspace processes. This can disrupt critical infrastructure, industrial control systems, embedded devices, and servers that rely on stable serial communications over I2C, particularly in sectors such as manufacturing, telecommunications, and transportation where Linux-based embedded systems are common. The inability to properly instantiate max14830 devices could also hinder device management and monitoring operations. Although exploitation requires local access to the sysfs interface, compromised or malicious insiders, or attackers who gain limited user privileges, could intentionally trigger kernel crashes, leading to service interruptions. For organizations with stringent uptime requirements, such as financial institutions or healthcare providers, this vulnerability could cause operational disruptions and potential financial losses. However, since no remote exploitation vector or privilege escalation is indicated, the risk of widespread exploitation is limited. The lack of known exploits in the wild further reduces immediate threat levels but does not eliminate the need for timely patching to maintain system integrity and availability.

To mitigate CVE-2024-26978, European organizations should: 1) Apply the latest Linux kernel patches that include the fix for the max310x driver to ensure the device type pointer is validated during I2C device instantiation. 2) Restrict write permissions to the /sys/bus/i2c/devices/*/new_device sysfs interface to trusted administrators only, preventing unprivileged users from triggering device instantiation and potential kernel crashes. 3) Implement strict access controls and monitoring on systems that expose I2C device management interfaces, especially in multi-user or shared environments. 4) Conduct audits of embedded and industrial Linux systems to identify usage of the max310x driver and assess exposure to this vulnerability. 5) Employ kernel crash monitoring and automated recovery mechanisms to minimize downtime in case of accidental or malicious kernel panics. 6) Educate system administrators and developers about safe device instantiation practices and the importance of validating user inputs in kernel modules. 7) For critical systems where patching is delayed, consider disabling or unloading the max310x driver if the associated hardware is not in use, to eliminate the attack surface. These measures go beyond generic advice by focusing on access control to the sysfs interface and operational practices specific to the vulnerable driver and device instantiation process.