CVE-2024-26632 is a vulnerability identified in the Linux kernel related to the block I/O (bio) subsystem. Specifically, the issue arises when iterating over an empty bio structure using the bio_for_each_folio_all macro. In this scenario, if the bio contains no data, the function bio_first_folio() improperly calls page_folio() on a NULL pointer, leading to a kernel oops (crash). The root cause is that the check for reaching the end of the bio was incorrectly placed in bio_next_folio(), rather than in bio_first_folio(). This flaw results in dereferencing a NULL pointer when the bio is empty, causing a denial of service due to kernel panic or crash. The fix involves moving the boundary check to bio_first_folio() and adding an unlikely() macro to the error case to optimize branch prediction. This vulnerability affects certain versions of the Linux kernel identified by specific commit hashes. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet. The vulnerability is technical and low-level, impacting kernel stability when handling empty bio structures during block I/O operations.

For European organizations relying on Linux-based systems, this vulnerability poses a risk of denial of service through kernel crashes when processing specific block I/O operations involving empty bio structures. Systems running affected kernel versions could experience unexpected reboots or service interruptions, potentially impacting critical infrastructure, servers, and embedded devices. While this vulnerability does not directly lead to privilege escalation or data leakage, the resulting instability can disrupt business operations, especially in environments with high availability requirements such as financial institutions, telecommunications, and cloud service providers. The impact is more pronounced in environments with automated or high-volume I/O workloads where empty bio structures might be encountered. Given the Linux kernel's widespread use across European industries, the risk of operational disruption is significant if unpatched systems are exploited, even unintentionally, by malformed I/O requests or faulty drivers.

To mitigate this vulnerability, European organizations should promptly update their Linux kernel to the patched versions that include the fix for CVE-2024-26632. Kernel updates should be tested in staging environments to ensure compatibility with existing workloads before deployment. Organizations should also audit their systems to identify those running affected kernel versions using the provided commit hashes. In addition, monitoring kernel logs for oops or panic messages related to bio iteration can help detect attempts to trigger this vulnerability. For critical systems where immediate patching is not feasible, implementing kernel live patching solutions can reduce exposure. Network segmentation and limiting access to systems that handle block I/O operations can reduce the attack surface. Finally, organizations should maintain robust backup and recovery procedures to minimize downtime in case of crashes.