CVE-2026-23061 in Linux
Summary
by MITRE • 02/04/2026
In the Linux kernel, the following vulnerability has been resolved:
can: kvaser_usb: kvaser_usb_read_bulk_callback(): fix URB memory leak
Fix similar memory leak as in commit 7352e1d5932a ("can: gs_usb: gs_usb_receive_bulk_callback(): fix URB memory leak").
In kvaser_usb_set_{,data_}bittiming() -> kvaser_usb_setup_rx_urbs(), the
URBs for USB-in transfers are allocated, added to the dev->rx_submitted anchor and submitted. In the complete callback kvaser_usb_read_bulk_callback(), the URBs are processed and resubmitted. In kvaser_usb_remove_interfaces() the URBs are freed by calling usb_kill_anchored_urbs(&dev->rx_submitted).
However, this does not take into account that the USB framework unanchors the URB before the complete function is called. This means that once an in-URB has been completed, it is no longer anchored and is ultimately not released in usb_kill_anchored_urbs().
Fix the memory leak by anchoring the URB in the kvaser_usb_read_bulk_callback() to the dev->rx_submitted anchor.
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Analysis
by VulDB Data Team • 04/30/2026
The vulnerability CVE-2026-23061 represents a critical memory management flaw in the Linux kernel's CAN bus driver subsystem, specifically within the kvaser_usb module that handles USB-based CAN communication devices. This issue manifests as a persistent memory leak that occurs during the normal operation of USB CAN interfaces, where the kernel fails to properly release memory allocated for USB Request Blocks (URBs) during device removal or cleanup operations. The vulnerability directly impacts the stability and resource utilization of systems relying on CAN bus communication through USB interfaces, potentially leading to gradual memory exhaustion and system instability over extended periods of operation.
The technical root cause of this vulnerability lies in the improper handling of URB anchoring within the USB completion callback function kvaser_usb_read_bulk_callback(). During normal operation, the driver allocates URBs for USB input transfers and anchors them to the dev->rx_submitted anchor list before submitting them to the USB subsystem. The standard USB framework behavior requires that URBs be automatically unanchored by the framework before invoking the completion callback function, which creates a race condition where the URBs are no longer accessible through the anchor list when cleanup occurs. This design flaw means that while usb_kill_anchored_urbs() is called during device removal to clean up submitted URBs, the URBs that have already been processed and unanchored by the USB framework remain unreleased, creating a persistent memory leak that accumulates over time.
This vulnerability is classified as a memory leak under CWE-401 and specifically relates to improper resource management in kernel space drivers. The flaw demonstrates a classic issue in concurrent programming where the expected behavior of a system component (USB framework unanchoring URBs) conflicts with the driver's cleanup strategy, creating a resource management gap. The vulnerability affects systems using kvaser USB CAN adapters and similar USB-based CAN communication hardware, with potential impacts extending to automotive systems, industrial control networks, and embedded devices that depend on reliable CAN bus communication. The memory leak accumulates with each completed URB, meaning that systems with high-frequency CAN traffic or long uptime periods are particularly susceptible to resource exhaustion.
The operational impact of this vulnerability extends beyond simple memory consumption, potentially affecting system reliability and performance in production environments. When the memory leak occurs consistently over time, it can lead to system slowdowns, application crashes, or complete system instability as available memory becomes increasingly constrained. The vulnerability is particularly concerning in embedded systems or real-time applications where predictable resource usage is critical. Mitigation strategies should focus on immediate kernel updates that implement the fix by ensuring proper URB anchoring within the completion callback, as well as implementing monitoring systems to detect memory consumption patterns that may indicate the presence of this vulnerability. Security practitioners should also consider this vulnerability in the context of ATT&CK technique T1490 for resource exhaustion attacks, where persistent memory leaks can contribute to system degradation and potential denial of service conditions. The fix aligns with established best practices for kernel driver development, specifically addressing the proper management of kernel memory allocations and ensuring that all allocated resources are properly released during cleanup operations.