CVE-2024-39492 is a high-severity vulnerability identified in the Linux kernel, specifically affecting the MediaTek command queue (mtk-cmdq) mailbox driver. The issue arises from improper handling of the return value of the function pm_runtime_get_sync() within the cmdq_mbox_shutdown() routine. Normally, pm_runtime_get_sync() returns 1 when the power management runtime state is already active, but the existing code incorrectly triggers a WARN_ON() warning for any return value other than less than zero (which indicates an error). This leads to unnecessary warning messages during mailbox shutdown, which could potentially mask or cause improper handling of power management states. The vulnerability is classified under CWE-252 (Unchecked Return Value), indicating that the system does not correctly check or handle the return value of a critical function. Although the description focuses on fixing a warning condition, the CVSS v3.1 score of 7.0 (high) with vector AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H suggests that exploitation could lead to significant confidentiality, integrity, and availability impacts. The attack vector is local (AV:L), requiring low privileges (PR:L) but high attack complexity (AC:H), and no user interaction (UI:N). This implies that an attacker with limited local access could exploit this flaw to cause severe system compromise, potentially leading to privilege escalation or denial of service. The fix involves adjusting the condition to only warn on negative return values, preventing false warnings and ensuring correct power management state handling. No known exploits are reported in the wild yet, and the affected Linux kernel versions are identified by specific commit hashes. This vulnerability highlights the importance of proper error handling in kernel power management code, especially in drivers interfacing with hardware components like MediaTek chipsets.

For European organizations, this vulnerability poses a significant risk, especially those relying on Linux-based systems with MediaTek hardware components, such as embedded devices, IoT infrastructure, or specialized industrial equipment. Exploitation could lead to unauthorized disclosure of sensitive data (confidentiality impact), unauthorized modification or corruption of system processes (integrity impact), and disruption of services or system crashes (availability impact). Given the local attack vector, insider threats or attackers who gain limited local access (e.g., through compromised user accounts or physical access) could leverage this flaw to escalate privileges or disrupt operations. This is particularly critical for sectors with stringent uptime and data protection requirements, such as finance, healthcare, telecommunications, and critical infrastructure operators. Additionally, the high attack complexity may limit widespread exploitation but does not eliminate targeted attacks against high-value assets. The absence of known exploits in the wild provides a window for proactive mitigation before active exploitation occurs.

European organizations should prioritize updating their Linux kernel to the patched versions that address CVE-2024-39492 as soon as they become available. Since the vulnerability involves kernel-level code, applying vendor-supplied kernel updates or recompiling the kernel with the fix is essential. For embedded or IoT devices using MediaTek chipsets, coordinate with hardware vendors to obtain firmware or kernel patches. Implement strict access controls to limit local user privileges and reduce the risk of local exploitation. Employ monitoring solutions to detect unusual kernel warnings or power management anomalies that could indicate exploitation attempts. Conduct thorough audits of devices running affected kernels to identify any unauthorized local access. In environments where immediate patching is not feasible, consider isolating vulnerable systems from untrusted users and networks to minimize exposure. Finally, maintain up-to-date asset inventories to quickly identify and remediate affected systems across the organization.