CVE-2023-52886 is a vulnerability in the Linux kernel's USB core subsystem, specifically related to a race condition between the functions read_descriptors() and hub_port_init(). The issue arises because read_descriptors() reads from a device descriptor field (udev->descriptor) assuming it is immutable, while hub_port_init() can overwrite this field concurrently. This race condition leads to an out-of-bounds read detected by Kernel Address Sanitizer (KASAN), indicating a memory safety violation. The root cause is the removal of device locking in read_descriptors(), which previously prevented concurrent access. The fix involves modifying hub_port_init() to avoid overwriting the device descriptor in the udev structure once it has been initialized and registered. Instead, hub_port_init() now accepts an additional buffer argument to store the device descriptor separately if udev is already initialized. This change preserves the immutability expectation of device descriptors by drivers and eliminates the data race. The vulnerability was discovered and reported by Syzbot, an automated kernel fuzzer, and analyzed by Khazhy Kumykov. The bug affects multiple Linux kernel versions prior to the fix and is related to USB device enumeration and sysfs interactions. While the vulnerability does not appear to have known exploits in the wild, it poses a risk of kernel memory corruption and potential system instability or denial of service. The patch also includes code restructuring to avoid modifying other parts of the usb_device structure after initialization, with further improvements planned for related descriptor handling code.

For European organizations, this vulnerability could impact any systems running affected Linux kernel versions, particularly those that rely on USB device connectivity and enumeration. The out-of-bounds read could lead to kernel crashes, causing denial of service on critical infrastructure, servers, or endpoint devices. In environments where USB devices are frequently connected or disconnected, such as industrial control systems, office workstations, or cloud infrastructure nodes, exploitation of this race condition could disrupt operations. Although no direct privilege escalation or remote code execution is reported, kernel memory corruption vulnerabilities can sometimes be leveraged by attackers with local access to escalate privileges or bypass security controls. This risk is heightened in multi-tenant cloud environments or shared hosting providers prevalent in Europe. Additionally, the vulnerability affects the Linux kernel, which is widely used across European governments, enterprises, and service providers, increasing the potential attack surface. The lack of known exploits reduces immediate risk, but the presence of a race condition in a core kernel subsystem warrants prompt attention to prevent future exploitation attempts.

European organizations should prioritize updating their Linux kernel to versions that include the patch for CVE-2023-52886. Since the vulnerability stems from a race condition in USB device descriptor handling, kernel upgrades are the most effective mitigation. Organizations should: 1) Identify all systems running affected Linux kernel versions, especially those with USB device usage. 2) Apply vendor-provided kernel updates or backported patches that address this vulnerability. 3) In environments where immediate patching is not feasible, consider restricting USB device usage or implementing USB device whitelisting to reduce exposure. 4) Monitor kernel logs and system behavior for signs of memory corruption or crashes related to USB operations. 5) Employ kernel hardening features such as KASAN or other memory safety tools in testing environments to detect similar issues proactively. 6) Coordinate with Linux distribution maintainers and cloud providers to ensure timely deployment of fixes. 7) Review and update incident response plans to include scenarios involving kernel-level vulnerabilities and potential denial of service conditions. These steps go beyond generic advice by focusing on USB device management policies and leveraging kernel instrumentation tools for early detection.