CVE-2021-47171 is a vulnerability identified in the Linux kernel specifically affecting the USB network driver for SMSC75xx devices (smsc75xx_bind function). The issue is a memory leak occurring when errors arise after memory allocation during the binding process of the USB network device driver. The vulnerability was reported by Syzbot, an automated kernel fuzzer, which detected that allocated memory was not freed properly in error handling paths within the smsc75xx_bind function. The backtrace indicates the leak happens during kernel memory allocation calls (kmalloc and kzalloc) in the driver code. This memory leak can lead to gradual exhaustion of kernel memory resources if the error conditions triggering the leak occur repeatedly, potentially degrading system stability and performance. The vulnerability does not appear to allow direct code execution or privilege escalation but can cause denial of service conditions through resource exhaustion. The affected component is the Linux kernel's USB network driver for SMSC75xx devices, which are USB-to-Ethernet adapters commonly used for network connectivity. The vulnerability was published on March 25, 2024, and no known exploits in the wild have been reported so far. No CVSS score has been assigned to this vulnerability yet.

For European organizations, the impact of CVE-2021-47171 primarily revolves around potential denial of service scenarios on Linux systems using affected USB network adapters. Organizations relying on Linux servers or workstations with SMSC75xx USB Ethernet devices could experience system instability or degraded network performance due to kernel memory leaks. This can be particularly impactful in environments where high availability and network reliability are critical, such as financial institutions, telecommunications providers, and critical infrastructure operators. Although the vulnerability does not directly compromise confidentiality or integrity, the resulting denial of service could disrupt business operations, cause downtime, and increase operational costs. Additionally, memory leaks in kernel space can sometimes be leveraged as part of more complex attack chains, although no such exploits are currently known. European organizations with large Linux deployments, especially those using USB network adapters for connectivity or redundancy, should consider this vulnerability in their risk assessments.

To mitigate CVE-2021-47171, organizations should apply the latest Linux kernel patches that address the memory leak in the smsc75xx_bind function as soon as they become available. Since no patch links are provided in the report, monitoring official Linux kernel mailing lists and vendor advisories for updates is critical. In the interim, organizations can reduce risk by auditing their use of SMSC75xx USB network adapters and considering alternative network interfaces if feasible. System administrators should also implement monitoring of kernel memory usage and system logs to detect abnormal memory consumption patterns that could indicate exploitation attempts or triggering of the leak. Additionally, limiting physical or remote access to systems to trusted users can reduce the chance of triggering the vulnerability through malicious USB device insertion or crafted device interactions. Incorporating this vulnerability into vulnerability management and patching cycles will ensure timely remediation. Finally, organizations should test kernel updates in controlled environments to avoid disruptions.