CVE-2024-26749 is a use-after-free vulnerability identified in the Linux kernel's USB gadget driver for Cadence USB 3 (cdns3). The flaw occurs in the function cdns3_gadget_ep_disable(), which is responsible for disabling USB endpoints. Specifically, the vulnerability arises due to incorrect ordering of operations: the function cdns3_gadget_ep_free_request() frees a memory structure pointed to by 'priv_req', but immediately after, list_del_init() is called on priv_req->list, which accesses memory that has already been freed. This results in a use-after-free condition, which can lead to undefined behavior including kernel crashes, memory corruption, or potential escalation of privileges if exploited. The kernel's Kernel Electric Fence (KFENCE) debugging tool detected this bug, confirming the use-after-free read in the linked list deletion routine. The fix involves reordering the calls so that list_del_init() is executed before the memory is freed, preventing access to freed memory. This vulnerability affects versions of the Linux kernel containing the vulnerable cdns3 USB gadget driver code prior to the patch. No known exploits are reported in the wild as of the publication date. The vulnerability is technical and low-level, impacting the USB gadget subsystem used primarily in embedded or specialized Linux systems that implement USB device functionality via the cdns3 controller driver.

For European organizations, the impact of CVE-2024-26749 depends largely on their use of Linux systems with the affected cdns3 USB gadget driver. This driver is typically found in embedded devices, IoT devices, or specialized hardware that uses the Cadence USB 3 controller to present USB device endpoints. Organizations deploying such devices in industrial control systems, telecommunications infrastructure, or specialized computing environments may be at risk. Exploitation could lead to kernel crashes causing denial of service or, in worst cases, privilege escalation allowing attackers to gain higher-level access to the system. This could compromise confidentiality, integrity, and availability of affected devices. Given the kernel-level nature of the flaw, successful exploitation could undermine the security of critical infrastructure or sensitive data processed by these devices. However, the lack of known exploits and the specialized nature of the affected driver somewhat limits the immediate widespread impact. Nonetheless, organizations using embedded Linux devices with this USB controller should prioritize patching to avoid potential targeted attacks.

1. Apply the official Linux kernel patches that reorder the list_del_init() and cdns3_gadget_ep_free_request() calls to eliminate the use-after-free condition. Monitor Linux kernel mailing lists and distributions for updates addressing CVE-2024-26749. 2. Identify and inventory all devices running Linux kernels with the cdns3 USB gadget driver, particularly embedded and IoT devices, and verify their kernel versions. 3. For devices that cannot be immediately patched, consider disabling USB gadget functionality if not required, or restrict physical and logical access to USB interfaces to reduce attack surface. 4. Employ kernel hardening techniques such as Kernel Electric Fence (KFENCE), Kernel Address Sanitizer (KASAN), or other memory safety tools during development and testing to detect similar issues early. 5. Monitor system logs for unusual kernel errors or crashes related to USB gadget endpoints, which may indicate attempted exploitation. 6. Collaborate with device vendors to ensure timely firmware and kernel updates are provided and applied. 7. Implement network segmentation and strict access controls around devices with embedded Linux to limit potential lateral movement if compromise occurs.