CVE-2021-47495 is a vulnerability identified in the Linux kernel's usbnet driver, which handles USB network devices. The issue arises from a lack of proper sanity checks on the 'maxpacket' parameter, which represents the maximum packet size for USB network transfers. Specifically, a 'maxpacket' value of zero is invalid and leads to a division by zero error within the driver code. This results in a kernel oops, effectively causing a denial of service (DoS) by crashing the kernel or the affected module. The vulnerability was addressed by adding a sanity check to ensure that 'maxpacket' is never zero, thereby preventing the division by zero condition. The fix also included corrections to logging and stylistic improvements in the code. The vulnerability affects multiple versions of the Linux kernel identified by specific commit hashes but does not have an assigned CVSS score, nor are there known exploits in the wild at the time of publication. The vulnerability is primarily a stability and availability issue rather than one that directly compromises confidentiality or integrity. Exploitation would require interaction with a vulnerable USB network device or driver, which may limit the attack surface to systems using such hardware and drivers.

For European organizations, the primary impact of CVE-2021-47495 is the potential for denial of service on Linux systems utilizing USB network devices managed by the usbnet driver. This could disrupt network connectivity, leading to downtime for critical services, especially in environments relying on Linux-based infrastructure for networking or embedded systems. Industrial control systems, telecommunications equipment, and IoT devices running Linux with usbnet support could be affected, potentially impacting operational continuity. While the vulnerability does not appear to allow privilege escalation or data compromise, the resulting system crashes could cause interruptions in business operations, data loss due to unexpected reboots, and increased operational costs due to system recovery efforts. The lack of known exploits reduces immediate risk, but the widespread use of Linux in European enterprises and public sector organizations means that unpatched systems remain vulnerable to accidental or targeted triggering of this flaw.

European organizations should implement the following specific mitigation measures: 1) Apply the official Linux kernel patches that address CVE-2021-47495 as soon as possible, ensuring that all affected systems are updated to a kernel version containing the fix. 2) Conduct an inventory of systems using USB network devices and assess whether the usbnet driver is in use; prioritize patching these systems. 3) Where patching is not immediately feasible, consider disabling or restricting the use of USB network devices to reduce exposure. 4) Implement monitoring for kernel oops or crashes related to usbnet to detect potential exploitation attempts or accidental triggers. 5) For embedded or specialized devices that cannot be easily updated, coordinate with vendors for firmware or kernel updates incorporating the fix. 6) Educate system administrators about the vulnerability and the importance of controlling physical access to USB ports to prevent malicious USB device insertion. These steps go beyond generic advice by focusing on the specific driver and hardware involved and emphasizing operational controls alongside patching.