CVE-2021-47269 is a vulnerability identified in the Linux kernel's USB driver subsystem, specifically within the DesignWare USB3 (dwc3) controller driver. The flaw arises due to a lack of validation on the endpoint index parameter in the function dwc3_wIndex_to_dep(), which is responsible for mapping an index to a USB endpoint. Without proper validation, the driver may reference a non-existent endpoint, leading to a NULL pointer dereference and consequent kernel NULL pointer exception (kernel oops). This can cause the kernel to crash or become unstable. The issue is particularly relevant in configurations where fewer endpoints are used than the index might indicate, such as in composite USB devices on older kernel versions. The vulnerability was fixed by adding validation checks that ensure the endpoint index is within valid bounds before dereferencing pointers, thereby preventing the NULL pointer exception. The technical details include kernel oops logs showing the faulting instruction and call trace, confirming the NULL pointer dereference in dwc3_ep0_handle_feature and dwc3_ep0_interrupt functions. The vulnerability affects Linux kernel versions prior to the patch and is relevant to systems using the dwc3 USB controller driver, which is common in embedded devices and some ARM-based platforms. No known exploits are reported in the wild, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2021-47269 primarily concerns systems running vulnerable Linux kernel versions with the dwc3 USB controller driver enabled. This includes embedded systems, IoT devices, and ARM-based servers or workstations that utilize this USB controller. The vulnerability can lead to kernel crashes, resulting in denial of service (DoS) conditions. In critical infrastructure or industrial control systems relying on such devices, this could cause operational disruptions. While the vulnerability does not directly enable privilege escalation or remote code execution, the resulting instability could be exploited by attackers with local access to disrupt services or cause system downtime. Organizations with Linux-based devices in their operational technology (OT) environments, or those using custom or older Linux kernels, are at higher risk. The lack of known exploits reduces immediate threat, but the potential for DoS and system instability necessitates prompt attention. Additionally, the proprietary nature of some hardware implementations may complicate detection and mitigation efforts.

1. Apply the official Linux kernel patches that address this vulnerability as soon as they become available for your specific kernel version and distribution. 2. For embedded or proprietary systems, coordinate with hardware vendors to obtain updated firmware or kernel versions that include the fix. 3. Implement kernel crash monitoring and automated recovery mechanisms to minimize downtime in case of a kernel oops. 4. Restrict local access to systems running vulnerable kernels to trusted personnel only, reducing the risk of exploitation. 5. Conduct thorough inventory and auditing of Linux systems to identify those using the dwc3 USB controller driver and verify kernel versions. 6. Where possible, disable unused USB endpoints or the dwc3 driver if the hardware configuration allows, reducing the attack surface. 7. Employ kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR) and kernel lockdown features to mitigate potential exploitation paths. 8. Maintain up-to-date backups and recovery plans for critical systems to ensure rapid restoration if a DoS occurs.