CVE-2026-10668
LowCVSS 2.4Exploitation Probability (EPSS)
Low risk5th percentile - higher than 5% of all known CVEs
Summary
In the Nuvoton NuMaker HSUSBD USB device-controller driver (udc_numaker.c), the control Data IN stage is unconditionally armed. When a USB host cancels an in-flight control transfer (timeout) and issues a new SETUP packet, the driver becomes out of sync, potentially sending stale data and permanently NAK'ing the control endpoint.
Risk Assessment
A malicious or buggy USB host (physical adjacent attacker) can repeatedly cancel and re-SETUP to wedge the device's USB control endpoint, causing denial of service (DoS) for the USB function. The device stops enumerating and responding on the control pipe until a USB reset or re-plug.
Recommendation
Update to a version containing the fix (v4.4.0 or later), which monitors IN-token and new-SETUP events and only arms control Data IN when an IN token is present and no new SETUP has arrived, canceling the current transfer on a new SETUP.
Original NVD description (English source)
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.