CVE-2024-42236 is a vulnerability identified in the Linux kernel's USB gadget subsystem, specifically within the configfs interface handling function usb_string_copy(). The vulnerability arises from insufficient validation of user-supplied strings, where a zero-length string can trigger an out-of-bounds (OOB) read and write. The problematic code attempts to access and modify the character immediately preceding the start of the string (str[-1]), which is invalid memory access. This leads to an OOB read when checking if str[-1] equals a newline character, followed by an OOB write when setting str[-1] to a null terminator. While the kernel already performs checks to prevent overly long strings, it lacked validation for strings that are too short, particularly zero-length strings. This flaw could potentially be exploited by a local user or process that can provide crafted input to the USB gadget configfs interface, causing memory corruption. Such corruption could lead to kernel crashes (denial of service) or potentially enable privilege escalation or arbitrary code execution if exploited with additional conditions. The vulnerability affects multiple versions of the Linux kernel identified by specific commit hashes. The issue was addressed by adding additional validation to reject invalid strings that are too short, preventing the OOB access. No known exploits are reported in the wild as of the publication date, and no CVSS score has been assigned yet.

For European organizations, this vulnerability poses a risk primarily to systems running Linux kernels with USB gadget support enabled and exposed to untrusted userspace inputs. This includes embedded devices, IoT systems, and servers that utilize USB gadget functionality for device emulation or testing. Exploitation could lead to kernel crashes, causing service disruptions and potential denial of service. More critically, if leveraged in combination with other vulnerabilities, it could allow attackers to escalate privileges or execute arbitrary code at the kernel level, compromising system confidentiality and integrity. This is particularly concerning for critical infrastructure, telecommunications, and industrial control systems prevalent in Europe that rely on Linux-based devices. The lack of known exploits currently reduces immediate risk, but the ease of triggering OOB reads/writes with crafted input suggests a moderate to high risk if attackers develop exploits. Organizations with Linux-based USB gadget configurations should prioritize patching to avoid potential exploitation and service interruptions.

1. Apply the official Linux kernel patches that address CVE-2024-42236 as soon as they become available from trusted sources or Linux distribution vendors. 2. Audit systems to identify those running Linux kernels with USB gadget support enabled, especially those exposed to untrusted users or automated input. 3. Restrict access to configfs and USB gadget interfaces to trusted users only, minimizing the attack surface. 4. Implement kernel hardening measures such as Kernel Address Space Layout Randomization (KASLR) and Kernel Page Table Isolation (KPTI) to reduce exploitation impact. 5. Monitor system logs for unusual kernel errors or crashes related to USB gadget operations that could indicate attempted exploitation. 6. For embedded or IoT devices, coordinate with vendors to ensure timely firmware updates incorporating the fix. 7. Employ network segmentation and strict access controls to isolate vulnerable devices from critical network segments. 8. Consider disabling USB gadget functionality on systems where it is not required to eliminate the attack vector.