CVE-2021-47098 is a vulnerability identified in the Linux kernel's hardware monitoring (hwmon) subsystem, specifically within the lm90 driver responsible for temperature sensor management. The issue pertains to integer overflow and underflow conditions during hysteresis temperature calculations. Previously, a commit (b50aa49638c7) addressed several underflow scenarios when writing temperature limits, but it failed to cover a particular edge case. This case occurs when the hysteresis value is set to the maximum long integer value (MAX_LONG) while the critical temperature limit is negative. Without proper clamping, this can cause integer overflow or underflow, potentially leading to incorrect temperature readings or limit settings. The vulnerability is mitigated by using the clamp_val() function to ensure the hysteresis temperature value remains within safe bounds, preventing overflow or underflow. Although this vulnerability affects the Linux kernel, it is limited to the hwmon lm90 driver code path and involves internal temperature limit calculations rather than direct user-facing interfaces. No known exploits are reported in the wild, and the vulnerability was published in March 2024. The affected versions correspond to the commit before the patch was applied. The vulnerability does not have an assigned CVSS score, and no evidence suggests it requires user interaction or authentication for exploitation. The impact is primarily on the integrity and reliability of temperature monitoring within affected Linux systems, which could potentially affect system stability or hardware protection mechanisms if exploited.

For European organizations, the impact of CVE-2021-47098 is primarily related to the reliability and stability of Linux-based systems that utilize the lm90 hardware monitoring driver. These systems are often embedded in servers, industrial control systems, or specialized hardware monitoring environments. Incorrect temperature readings or failure to enforce temperature limits due to integer overflow/underflow could lead to hardware overheating, premature hardware failure, or unexpected system shutdowns. This could disrupt critical infrastructure, manufacturing processes, or data center operations. However, the vulnerability does not appear to allow remote code execution or privilege escalation directly. The absence of known exploits reduces immediate risk, but organizations relying on Linux kernel versions prior to the patch should consider the potential for hardware damage or operational disruption. European sectors with high dependence on Linux-based embedded systems, such as manufacturing, energy, telecommunications, and research institutions, may be more affected. The impact is less critical for general-purpose Linux desktop or server environments unless they specifically use the affected hwmon driver and hardware sensors.

European organizations should apply the Linux kernel patch that includes the commit fixing this vulnerability, ensuring the use of clamp_val() in hysteresis temperature calculations within the lm90 driver. Kernel updates should be prioritized on systems running hardware that uses the lm90 sensor driver, especially in industrial or embedded environments. Organizations should audit their Linux kernel versions and hardware monitoring configurations to identify affected systems. Additionally, monitoring system logs for temperature sensor anomalies or hardware warnings can help detect potential exploitation or misbehavior. For critical infrastructure, implementing hardware-level temperature monitoring and alerts independent of the Linux kernel can provide an additional safety layer. Vendors providing Linux-based embedded systems should be engaged to confirm patch availability and deployment timelines. Finally, maintaining a robust patch management process and verifying kernel integrity post-update will reduce exposure to this vulnerability.