CVE-2025-37840 is a vulnerability identified in the Linux kernel specifically affecting the raw NAND flash memory driver for Broadcom NAND controllers (brcmnand). The issue arises during the power management (PM) resume operation where an uninitialized nand_operation structure is used, leading to a warning triggered by the kernel's WARN_ON macro. This warning indicates that the chip select (cs) field in the nand_operation structure is out of bounds relative to the number of NAND targets supported by the chip. The root cause is the use of the lower-level nand_reset_op() function with an uninitialized operation structure during PM resume, which does not properly handle the chip select field. The fix involves switching to the higher-level nand_reset() function with a chip number of zero, aligning with the controller's support for single-die NAND chips and ensuring proper initialization. This correction prevents kernel warnings and potential instability during resume from suspend states. Although the vulnerability primarily manifests as a kernel warning, it indicates improper handling of NAND operations that could potentially lead to undefined behavior or system instability on affected devices. The vulnerability affects Linux kernel versions identified by the commit hash 97d90da8a886949f09bb4754843fb0b504956ad2 and similar builds. No known exploits are reported in the wild, and no CVSS score has been assigned yet. The vulnerability is technical and specific to embedded systems or devices using Broadcom NAND controllers with Linux kernel support, particularly during power management transitions.

For European organizations, the impact of CVE-2025-37840 is primarily relevant to those deploying embedded Linux systems or devices that utilize Broadcom NAND flash memory controllers, such as set-top boxes, network appliances, or IoT devices. The vulnerability could cause kernel warnings and potential instability during system resume from suspend states, which may lead to device crashes or degraded performance. This could affect operational continuity in environments relying on such embedded devices, including telecommunications infrastructure, industrial control systems, or consumer electronics. While no direct evidence suggests this vulnerability leads to privilege escalation or remote code execution, the improper handling of NAND operations during power management could be exploited in complex attack chains or cause denial of service conditions. European organizations with critical infrastructure or supply chains dependent on embedded Linux devices should be aware of this vulnerability to avoid unexpected downtime or hardware malfunctions. The lack of known exploits reduces immediate risk, but the potential for system instability warrants timely patching to maintain reliability and security compliance.

To mitigate CVE-2025-37840, European organizations should: 1) Identify all embedded Linux devices and systems using Broadcom NAND controllers, particularly those running affected kernel versions. 2) Apply the official Linux kernel patches or updates that replace nand_reset_op() calls with nand_reset() during PM resume operations. If vendor-specific firmware updates are available for affected devices, deploy them promptly. 3) For custom or in-house Linux builds, integrate the patch corresponding to commit 97d90da8a886949f09bb4754843fb0b504956ad2 or later stable releases that include the fix. 4) Conduct thorough testing of power management suspend/resume cycles post-patching to ensure system stability and absence of kernel warnings. 5) Monitor kernel logs for any residual warnings related to NAND operations to detect incomplete remediation. 6) Implement device inventory and configuration management to track vulnerable systems and ensure timely updates. 7) For critical infrastructure, consider network segmentation and access controls to limit exposure of embedded devices to potential attackers. These steps go beyond generic advice by focusing on embedded device identification, patch integration, and operational validation specific to this vulnerability.