CVE-2025-37859 is a vulnerability identified in the Linux kernel's page_pool subsystem, specifically related to the handling of delayed worker scheduling in the page_pool_release_retry() function. The issue arises when a buggy driver causes the 'inflight' counter, which tracks the number of packet-pages currently in use, to become negative. This negative inflight value is an abnormal state indicating a logic error in resource accounting. Due to this, the kernel's worker thread (kworker) responsible for releasing page pool resources is repeatedly and infinitely rescheduled, causing an infinite loop. This results in excessive CPU usage and flooding of kernel logs (dmesg) with warning messages and call traces, which can degrade system performance and stability. The patch introduced mitigates the problem by preventing the rescheduling of the kworker when a negative inflight value is detected, thus avoiding the infinite loop and associated resource exhaustion. The vulnerability is rooted in kernel resource management and is triggered by faulty drivers that mishandle packet-page accounting, leading to system instability. No CVSS score has been assigned yet, and there are no known exploits in the wild as of the publication date.

For European organizations, this vulnerability poses a risk primarily to systems running affected Linux kernel versions with drivers that could trigger the negative inflight condition. The impact includes potential denial of service due to high CPU consumption by the infinite kworker loop and log flooding, which can obscure other critical system messages and complicate troubleshooting. This can affect servers, network appliances, and embedded devices relying on Linux, potentially disrupting business operations, especially in sectors with high availability requirements such as finance, telecommunications, and critical infrastructure. While the vulnerability does not directly expose confidentiality or integrity risks, the availability impact can be significant, leading to service outages or degraded performance. Organizations using custom or third-party drivers should be particularly vigilant, as buggy drivers are the root cause. The lack of known exploits reduces immediate risk, but the vulnerability's nature means that exploitation could be achieved by local attackers or automated processes triggering the faulty driver behavior.

European organizations should prioritize updating their Linux kernels to versions that include the patch for CVE-2025-37859 as soon as they become available. In the interim, auditing and validating all third-party and custom kernel drivers for correctness in resource accounting is critical to prevent triggering the negative inflight condition. System administrators should monitor kernel logs for signs of repeated page_pool warnings or kworker rescheduling loops to detect potential exploitation or triggering of this vulnerability. Implementing kernel live patching where possible can reduce downtime during remediation. Additionally, organizations should enforce strict driver vetting policies and consider isolating or sandboxing untrusted drivers to limit impact. For critical systems, deploying monitoring tools that track CPU usage spikes and kernel worker thread behavior can provide early warning signs. Finally, maintaining robust backup and recovery procedures will help mitigate the impact of any availability disruptions caused by this issue.