CVE-2025-22125 is a vulnerability identified in the Linux kernel's md (multiple device) RAID1 and RAID10 implementations. The issue arises from the mishandling of IO flags, specifically the ignoring of certain flags such as REQ_IDLE, REQ_META, and REQ_NOWAIT during block device write operations. The blk-wbt (block writeback throttling) feature, when enabled by default, causes all IO operations to be throttled by the writeback throttling mechanism of the underlying disks. This results in degraded RAID write performance because the REQ_IDLE flag, which signals that the IO can be delayed or deprioritized, was ignored. Additionally, other flags like REQ_META, which indicates metadata IO and affects IO prioritization, and REQ_NOWAIT, which controls whether IO should fail immediately if it cannot be processed, were also improperly cleared. This mishandling can lead to priority inversion problems and unexpected IO blocking behavior. The fix involves preserving these IO flags from the master bio structure to ensure correct IO scheduling and priority handling. This vulnerability affects Linux kernel versions identified by the commit hash 5404bc7a87b9949cf61e0174b21f80e73239ab25 and was publicly disclosed on April 16, 2025. There are no known exploits in the wild at the time of publication, and no CVSS score has been assigned yet.

For European organizations, this vulnerability can lead to significant performance degradation in systems utilizing Linux software RAID1 or RAID10 configurations, especially where blk-wbt is enabled by default. The throttling of IO operations can slow down critical data write processes, potentially impacting database servers, file servers, and other storage-intensive applications. While this vulnerability does not directly lead to data corruption or unauthorized access, the performance impact can affect service availability and operational efficiency. Organizations relying on Linux-based storage solutions for high-availability or real-time data processing may experience increased latency and throughput reduction, which could indirectly affect business continuity and user experience. Given the widespread use of Linux in European enterprise environments, including cloud infrastructure providers, telecommunications, and public sector IT systems, the performance degradation could have cascading effects on dependent services and applications.

To mitigate this vulnerability, European organizations should promptly apply the Linux kernel patch that preserves the IO flags in the md RAID1 and RAID10 code paths. System administrators should verify that their Linux kernel versions include the fix referenced by commit f51d46d0e7cb or later. Additionally, organizations should audit their systems to determine if blk-wbt is enabled by default and assess the impact on RAID write performance. If upgrading the kernel is not immediately feasible, temporarily disabling blk-wbt or adjusting its parameters to reduce throttling may help alleviate performance issues. Monitoring RAID performance metrics and IO latency can help detect symptoms of this vulnerability. Furthermore, organizations should maintain robust testing environments to validate kernel updates before deployment to production systems to avoid unintended disruptions.