# CVE-2026-10668: Host-triggerable control-endpoint wedge (DoS) in Nuvoton NuMaker HSUSBD UDC driver

Status: published. Published: 2026-07-12. Updated: 2026-11-04.

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

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: zephyr) — https://github.com/zephyrproject-rtos/zephyr/commit/48e003326873e8bbc0ee4b67334e0dd8b5fb890f

## Affected products and versions

- zephyrproject / zephyr (zephyr): ≥ 4.4.0; < 4.4.2 (affected, semver). Source: CNA: zephyr

## Severity and prioritization

- CVSS 3.1: 2.4 (low); CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L; source: CNA: zephyr

- CISA KEV: No listing in collected sources

- EPSS: 0.23% as of 2026-11-03; percentile 13.95%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-400

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/zephyrproject-rtos/zephyr/commit/48e003326873e8bbc0ee4b67334e0dd8b5fb890f (CNA: zephyr; patch)

- https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-rm28-x84j-4qrx (CNA: zephyr)

## Provenance

- CNA: zephyr: https://www.cve.org/CVERecord?id=CVE-2026-10668; retrieved 2026-11-04; source updated 2026-11-04

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-10668; retrieved 2026-11-04; source updated Not reported

Revision: 8e62472babf152e67138606a233e10e84a40084970953b8b96807c052a2fc396

Canonical: https://y2.dev/cve/CVE-2026-10668

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.