CVE-2026-10668 Host-triggerable control-endpoint wedge (DoS) in Nuvoton NuMaker HSUSBD UDC driver
A malicious USB host can wedge the control endpoint of Nuvoton NuMaker devices, causing a denial of service until reset.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-10668?
CVE-2026-10668 is a low-severity denial of service vulnerability in Zephyrproject Zephyr, published on 12 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-400
Which versions are affected by CVE-2026-10668?
It affects 1 product.
Products include Zephyrproject Zephyr.
How do I fix CVE-2026-10668?
No fix has been published for CVE-2026-10668 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-10668 being exploited?
There is no known exploitation of CVE-2026-10668 in the wild and no public exploit code.
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Sources
Also known as GHSA-rm28-x84j-4qrx.