CVE-2022-48747 is a high-severity vulnerability in the Linux kernel related to the block device layer, specifically in the bio_truncate() function. This function is responsible for truncating block I/O (bio) structures, which represent block device I/O requests. The vulnerability arises because bio_truncate() uses an incorrect offset when clearing buffers outside the last block of a block device (bdev). As a result, it can return uninitialized data when both a truncated or corrupted filesystem and userspace applications attempt to read the last block of the block device. This flaw leads to an information disclosure issue where sensitive data from kernel memory or previously stored data could be leaked to unauthorized userspace processes. The vulnerability is classified under CWE-908 (Use of Uninitialized Variable), indicating that uninitialized memory is exposed due to improper offset calculation. The CVSS v3.1 score is 7.5 (high), with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), and high impact on confidentiality (C:H), but no impact on integrity or availability (I:N/A:N). No known exploits are currently reported in the wild, but the vulnerability affects multiple Linux kernel versions identified by their commit hashes. Since Linux is widely used in servers, cloud infrastructure, embedded systems, and desktops, this vulnerability could have broad implications if exploited. The root cause is a logic error in bio_truncate() that mishandles page offsets during truncation, leading to exposure of uninitialized memory contents when reading the last block of a block device under certain filesystem corruption or truncation conditions.

For European organizations, this vulnerability poses a significant risk of sensitive data leakage from Linux-based systems, which are prevalent in enterprise servers, cloud environments, and critical infrastructure. Confidential information such as cryptographic keys, passwords, or other sensitive data residing in kernel memory or previously stored on block devices could be exposed to unauthorized userspace processes. This could lead to data breaches, compliance violations (e.g., GDPR), and loss of trust. Since no privileges or user interaction are required to exploit this vulnerability, attackers could remotely trigger reads that leak data if they have network access to affected systems. The impact is particularly critical for sectors relying heavily on Linux servers such as finance, telecommunications, healthcare, and government agencies in Europe. Additionally, cloud service providers and hosting companies operating Linux-based infrastructure in Europe could see increased risk if attackers leverage this flaw to extract sensitive tenant data. Although no known exploits exist yet, the ease of exploitation and high confidentiality impact warrant urgent attention.

European organizations should immediately verify that their Linux kernel versions are patched against CVE-2022-48747. Applying the latest Linux kernel updates from trusted sources is the primary mitigation step. For environments where immediate patching is not feasible, organizations should restrict access to block devices, especially limiting untrusted userspace processes from reading raw block devices or the last blocks of storage devices. Monitoring and auditing filesystem integrity to detect corruption or truncation conditions can reduce the likelihood of triggering the vulnerability. Employing kernel security modules (e.g., SELinux, AppArmor) to enforce strict access controls on block device interfaces can further mitigate risk. Network segmentation and firewall rules should limit exposure of vulnerable Linux systems to untrusted networks. Additionally, organizations should review and enhance logging to detect suspicious read attempts on block devices. Finally, security teams should prepare incident response plans for potential data leakage scenarios stemming from this vulnerability.