CVE-2024-26982 is a vulnerability identified in the Linux kernel's Squashfs filesystem implementation. Squashfs is a compressed, read-only filesystem commonly used in embedded systems, live Linux distributions, and other environments where space efficiency is critical. The vulnerability arises from an improper validation of inode numbers during metadata indexing operations. Specifically, the function fill_meta_index() is responsible for allocating and populating metadata indexes. If a data read error occurs during this process, fill_meta_index() aborts and marks the newly allocated metadata index as invalid by setting its inode number to zero. However, zero is not a valid inode number in Linux filesystems. Subsequently, when fill_meta_index() is called again, the locate_meta_index() function mistakenly returns the previously invalidated index because it matches the inode number zero. This index is expected to be valid and filled, but since it is not, an out-of-bounds memory access occurs. This out-of-bounds access can lead to undefined behavior, including potential kernel crashes (denial of service) or memory corruption, which could be leveraged for privilege escalation or arbitrary code execution in certain scenarios. The patch for this vulnerability introduces a sanity check that prevents the creation of inodes with an invalid inode number of zero by returning an error (-EINVAL) if such a condition is detected. This check effectively mitigates the root cause of the out-of-bounds access. No known exploits are currently reported in the wild, and the vulnerability was published on May 1, 2024. The affected versions correspond to specific Linux kernel commits prior to the patch. Since this vulnerability involves kernel-level memory corruption, it is critical to address it promptly in affected systems.

For European organizations, the impact of CVE-2024-26982 can be significant, especially for those relying on Linux-based systems that utilize the Squashfs filesystem. This includes embedded devices, network appliances, live boot environments, and containerized applications that may use Squashfs images. The out-of-bounds access vulnerability could be exploited to cause kernel panics, leading to denial of service and system downtime. In more severe cases, if an attacker can craft malicious Squashfs images or manipulate filesystem metadata, there is potential for privilege escalation or arbitrary code execution at the kernel level, compromising system integrity and confidentiality. This risk is particularly relevant for critical infrastructure, telecommunications, and industrial control systems prevalent in Europe that depend on Linux. Additionally, the disruption caused by kernel crashes can affect business continuity, data availability, and operational technology environments. Given the widespread use of Linux in European public and private sectors, failure to patch this vulnerability could expose organizations to targeted attacks or accidental system failures.

European organizations should implement the following specific mitigation steps: 1) Identify all Linux systems using Squashfs, particularly those running kernel versions prior to the patch commit referenced by CVE-2024-26982. 2) Apply the official Linux kernel patch that adds the inode number sanity check or upgrade to a kernel version that includes this fix. 3) For embedded devices or appliances where kernel upgrades are challenging, coordinate with vendors to obtain firmware updates that address this vulnerability. 4) Implement strict validation and integrity checks on Squashfs images before deployment, ensuring they are sourced from trusted origins and scanned for anomalies. 5) Monitor kernel logs and system behavior for signs of out-of-bounds access or unexpected crashes related to filesystem operations. 6) Employ kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR) and Kernel Page Table Isolation (KPTI) to reduce exploitation risk. 7) Restrict access to systems that can mount or manipulate Squashfs images to trusted administrators to limit attack surface. 8) Incorporate this vulnerability into vulnerability management and patching workflows to ensure timely remediation.