CVE-2021-47258 is a vulnerability identified in the Linux kernel's SCSI (Small Computer System Interface) core subsystem. The issue arises from improper error handling in the function scsi_host_alloc(), specifically related to the lifecycle management of device structures. When a device is initialized using device_initialize() or its name is set via dev_set_name(), the device must be properly released using put_device() to avoid memory leaks. The vulnerability occurs because the existing error handling incorrectly uses kfree() instead of put_device() to free the device, leading to a memory leak of the device name, which is dynamically allocated during dev_set_name(). Additionally, the patch removes special-case handling for IDA (ID allocator) and kernel thread removal in the error path, as these are already correctly managed in scsi_host_dev_release(). Although this vulnerability results in a memory leak rather than direct code execution or privilege escalation, it can degrade system stability over time, especially on systems with frequent SCSI device initialization and teardown. The vulnerability affects specific Linux kernel versions identified by the commit hash 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and was published on May 21, 2024. There are no known exploits in the wild at this time, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2021-47258 is primarily related to system reliability and availability. Systems running vulnerable Linux kernel versions that heavily utilize SCSI devices—such as storage servers, SAN (Storage Area Network) infrastructure, and enterprise-grade Linux deployments—may experience gradual memory leaks leading to resource exhaustion. Over time, this can cause degraded performance, system instability, or crashes, potentially disrupting critical business operations. While this vulnerability does not directly expose confidential data or allow unauthorized access, the indirect effects on availability could impact services reliant on Linux-based storage or compute infrastructure. Organizations in sectors such as finance, healthcare, telecommunications, and cloud service providers, which often deploy Linux servers with SCSI devices, should be particularly mindful. The absence of known exploits reduces immediate risk, but the vulnerability should be addressed proactively to maintain system integrity and prevent potential future exploitation or cascading failures.

To mitigate CVE-2021-47258, European organizations should: 1) Apply the official Linux kernel patches that replace kfree() with put_device() in the scsi_host_alloc() error handling path as soon as they become available from their Linux distribution vendors. 2) Regularly update Linux kernel versions to incorporate security fixes and improvements, prioritizing systems with heavy SCSI device usage. 3) Implement monitoring of system memory usage and kernel logs to detect unusual memory consumption patterns or device initialization errors that could indicate the presence of this leak. 4) For critical systems, consider isolating or limiting frequent SCSI device initialization operations until patches are applied. 5) Engage with Linux distribution security advisories and subscribe to relevant mailing lists to receive timely updates on kernel vulnerabilities. 6) Test patches in staging environments to ensure compatibility and stability before deployment in production. These steps go beyond generic advice by focusing on proactive patch management, targeted monitoring, and operational adjustments specific to the nature of this vulnerability.