CVE-2025-21952 is a vulnerability identified in the Linux kernel, specifically related to the handling of power supply values for Corsair Void devices within the Human Interface Device (HID) subsystem. The root cause of the vulnerability lies in the function corsair_void_process_receiver, which can be invoked from an interrupt context. Within this function, the kernel attempts to lock a mutex (battery_mutex) to protect critical sections of code. However, locking a mutex in an interrupt context is unsafe and leads to a kernel panic, effectively causing a denial of service (DoS) by crashing the kernel. The fix implemented involves refactoring the code to move the critical section into a dedicated work handler that is shared with other battery-related work functions (battery_add_work and battery_remove_work). This change eliminates the need for locking within the interrupt context, thereby preventing the kernel panic. The vulnerability affects specific Linux kernel versions identified by the commit hash 6ea2a6fd3872e60a4d500b548ad65ed94e459ddd. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The issue is primarily a stability and availability concern, as it can cause system crashes when the affected HID device is used under certain conditions.

For European organizations, the impact of CVE-2025-21952 centers on system availability and operational continuity. Linux is widely used across Europe in enterprise servers, cloud infrastructure, embedded systems, and workstations. Organizations utilizing Corsair Void devices on Linux systems—commonly in office environments or specialized setups—may experience unexpected kernel panics leading to system downtime. This can disrupt business operations, especially in sectors relying on high availability such as finance, telecommunications, healthcare, and manufacturing. Additionally, kernel panics can lead to data loss or corruption if they occur during critical operations. While this vulnerability does not appear to allow privilege escalation or data breaches directly, the denial of service aspect can be exploited by attackers with local access or through crafted device interactions to degrade system reliability. Given the prevalence of Linux in critical infrastructure and the increasing use of HID peripherals, the vulnerability poses a moderate risk to European organizations that have not applied the patch or mitigations.

To mitigate CVE-2025-21952, European organizations should take the following specific actions: 1) Identify Linux systems running kernel versions that include the vulnerable commit (6ea2a6fd3872e60a4d500b548ad65ed94e459ddd) or earlier versions that have not incorporated the fix. 2) Apply the official Linux kernel patch that refactors the corsair_void_process_receiver function to use a unified work handler, as soon as it is available from trusted sources or distributions. 3) If immediate patching is not feasible, consider temporarily disabling or avoiding the use of Corsair Void HID devices on affected systems to prevent triggering the kernel panic. 4) Monitor system logs and kernel messages for signs of unexpected panics or crashes related to HID device activity. 5) Implement robust backup and recovery procedures to minimize data loss in case of crashes. 6) Engage with Linux distribution vendors or maintainers to ensure timely updates and backports of the fix to long-term support kernels. 7) For environments with strict uptime requirements, test the patch in staging before deployment to avoid regressions. These steps go beyond generic advice by focusing on device-specific mitigation and operational continuity.