---
id: CVE-2026-10668
title: >-
  The Nuvoton NuMaker HSUSBD USB device-controller driver
  (drivers/usb/udc/udc_numaker.c) armed the control Data IN stage
  unconditionally (base->CEPTXCNT = len in numaker_hsusbd_ep_trigger)
summary: >-
  The Nuvoton NuMaker HSUSBD USB device-controller driver
  (drivers/usb/udc/udc_numaker.c) armed the control Data IN stage
  unconditionally (base->CEPTXCNT = len in numaker_hsusbd_ep_trigger). Because
  the HSUSBD hardware cannot disarm a cont…
severity: low
cvss: 2.4
cvssVector: 'CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-400
published: '2026-07-12'
updated: '2026-07-12'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-10668'
references:
  - url: >-
      https://github.com/zephyrproject-rtos/zephyr/commit/48e003326873e8bbc0ee4b67334e0dd8b5fb890f
    label: vulnerabilities@zephyrproject.org
  - url: >-
      https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-rm28-x84j-4qrx
    label: vulnerabilities@zephyrproject.org
tags:
  - nvd
ingestedAt: '2026-07-12T17:20:29.696Z'
epss: 0.0023
epssPercentile: 0.12315
---

## Overview

The Nuvoton NuMaker HSUSBD USB device-controller driver (drivers/usb/udc/udc_numaker.c) armed the control Data IN stage unconditionally (base->CEPTXCNT = len in numaker_hsusbd_ep_trigger). Because the HSUSBD hardware cannot disarm a control Data IN already armed for a previous transfer, a USB host that cancels an in-flight control transfer (timeout) and then issues a new SETUP packet can drive the driver out of sync: stale data may be transmitted in the new transfer and the control endpoint can become permanently stuck NAK'ing every subsequent control transfer.

A malicious or buggy host (physical/adjacent attacker driving the bus) can repeatedly cancel-and-re-SETUP to wedge the device's USB control endpoint, denying service to the device's USB function (the device stops enumerating/responding on the control pipe) until a USB reset or re-plug. The flaw is an availability-only denial of service; the FIFO copy loops (bounded by net_buf length and the hardware BUFFULL flag) and the net_buf lifecycle are independent of the arming desync, so there is no out-of-bounds access, use-after-free, or information leak.

The fix monitors the IN-token and new-SETUP events (k_event) and only arms control Data IN when an IN token is present and no new SETUP has arrived, cancelling the current transfer on a new SETUP. Affects boards using the Nuvoton NuMaker HSUSBD controller (CONFIG_UDC_NUMAKER with DT_HAS_NUVOTON_NUMAKER_HSUSBD_ENABLED); shipped in v4.4.0.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.