# CVE-2026-10656: NULL-pointer dereference DoS in MAX32 USB device controller transfer-completion handlers

> A USB host can crash Zephyr-based devices by aborting control transfers, causing a null pointer dereference in the MAX32 USB driver.

- **Severity:** Medium 4.6 (`CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Jul 2026
- **Updated:** 15 Oct 2026
- **Also known as:** GHSA-58p9-6mjq-rf2m

## What is CVE-2026-10656?

CVE-2026-10656 is a medium-severity vulnerability in Zephyrproject Zephyr, published on 5 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The MAX32xxx USB device controller driver (drivers/usb/udc/udc_max32.c, compatible adi_max32_usbhs) dereferenced an endpoint buffer in its OUT and IN transfer-completion handlers without checking it for NULL. udc_event_xfer_out_done() called net_buf_add(buf, ep_request->actlen) immediately after buf = udc_buf_get(ep_cfg), where udc_buf_get() returns NULL when the endpoint FIFO is empty.

A transfer-completion event is queued from interrupt context and processed asynchronously by the driver thread; between queuing and processing, the endpoint FIFO can be drained by host-controlled control flow — in particular udc_setup_received() drains the EP0 OUT/IN FIFOs whenever a new SETUP packet arrives, and dequeue/disable/purge paths drain it likewise.

A USB host that aborts an in-flight EP0 control transfer with a new SETUP packet (legal USB behavior) can therefore cause a stale XFER_OUT_DONE event to be processed against an empty FIFO, producing net_buf_add(NULL, ...), a near-NULL pointer dereference that faults and crashes the device. No authentication is required; the attacker is the USB host the device is connected to (physical bus access). Impact is denial of service (device crash).

The defect was introduced when the MAX32 UDC driver was added and shipped in Zephyr v4.4.0. The fix adds NULL-buffer checks that return early with UDC_EVT_ERROR/-ENOBUFS in both the OUT-done and IN-done handlers.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-10656?

It affects 1 product.


Products: Zephyrproject Zephyr.

## How do I fix CVE-2026-10656?

No fix has been published for CVE-2026-10656 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-10656 being exploited?

There is no known exploitation of CVE-2026-10656 in the wild and no public exploit code.

## Other vulnerabilities in Zephyrproject Zephyr

- [CVE-2026-5067](https://insights.sbomify.com/CVE-2026-5067/): Out-of-bounds read/write in HTTP WebSocket upgrade via non-null-terminated Sec-WebSocket-Key (critical 9.8)
- [CVE-2022-3806](https://insights.sbomify.com/CVE-2022-3806/): Bluetooth HCI Error Handling Double Free (critical 9.8)
- [CVE-2017-14199](https://insights.sbomify.com/CVE-2017-14199/): Memory corruption in getaddrinfo (critical 9.8)
- [CVE-2018-1000800](https://insights.sbomify.com/CVE-2018-1000800/): Null dereference in n/a (critical 9.8)
- [CVE-2021-3329](https://insights.sbomify.com/CVE-2021-3329/): DOS: Incorrect handling of the initial HCI ACL_MTU handshake packet leads to crash of bluetooth host layer (critical 9.6)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-10656 and fix it if it is affected.

What it is: CVE-2026-10656 is a medium-severity vulnerability in Zephyrproject Zephyr, published on 5 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-10656 in the wild and no public exploit code.

Affected product: Zephyrproject Zephyr. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-10656/ (Markdown: https://insights.sbomify.com/CVE-2026-10656/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-10656
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-10656
- OSV: https://osv.dev/vulnerability/CVE-2026-10656

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-10656/
Summaries are generated and may contain mistakes; the official description above is the record.