CVE-2025-23136 is a vulnerability identified in the Linux kernel's thermal management subsystem, specifically related to the int340x driver family that handles ACPI thermal zones on certain hardware platforms. The issue arises because the int3402_thermal_probe() function does not properly check whether the ACPI device pointer (adev) is NULL before dereferencing it. This can occur because not all devices have an ACPI companion firmware node (fwnode), meaning adev might be unset (NULL). Without this check, the kernel may dereference a NULL pointer, leading to a kernel crash (NULL pointer dereference) and thus a denial of service (DoS). The vulnerability is similar to a previously fixed issue in the int3472 driver where a NULL check was added for adev. The patch for this vulnerability adds a check for adev being NULL and returns -ENODEV to safely handle the condition, preventing the kernel from crashing. This vulnerability affects specific Linux kernel versions identified by the commit hash 77e337c6e23e3b9d22e09ffec202a80f755a54c2. There are no known exploits in the wild at the time of publication, and no CVSS score has been assigned yet. The vulnerability does not appear to allow privilege escalation or arbitrary code execution but can cause system instability or denial of service due to kernel panic triggered by the NULL pointer dereference in the thermal driver probe function.

For European organizations, the primary impact of CVE-2025-23136 is the risk of denial of service on Linux systems running affected kernel versions with hardware that uses the int340x thermal driver family. This could lead to unexpected system crashes or reboots, potentially disrupting critical services, especially in environments relying on Linux servers or embedded systems for infrastructure, industrial control, or cloud services. While the vulnerability does not directly expose data confidentiality or integrity risks, availability is affected. Organizations in sectors such as finance, healthcare, telecommunications, and manufacturing that depend on Linux-based systems for operational continuity could experience service interruptions. Additionally, the vulnerability could be exploited by local attackers or malicious software to cause system instability, which might be leveraged as part of a broader attack chain. However, exploitation requires the presence of specific hardware and affected kernel versions, limiting the scope somewhat. Since no known exploits exist yet, the immediate threat is low, but patching is recommended to prevent future exploitation.

To mitigate CVE-2025-23136, European organizations should: 1) Identify Linux systems running the affected kernel versions, especially those deployed on hardware platforms using the int340x ACPI thermal drivers. 2) Apply the official Linux kernel patches that add the NULL check for the ACPI device pointer in int3402_thermal_probe(), or upgrade to a kernel version where this fix is included. 3) For systems where kernel upgrades are not immediately feasible, consider disabling or blacklisting the int3402 thermal driver module if thermal management is not critical or can be handled by alternative means, to prevent the vulnerable code from executing. 4) Implement monitoring to detect kernel crashes or thermal driver failures that could indicate attempted exploitation or system instability. 5) Maintain strict access controls and limit local user privileges to reduce the risk of local exploitation attempts. 6) Coordinate with hardware vendors to confirm compatibility and support for patched kernels. These steps go beyond generic advice by focusing on hardware-specific driver management and proactive system monitoring.