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.
- 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-2026-10656?
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
Which versions are affected by CVE-2026-10656?
It affects 1 product.
Products include 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.
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Sources
Also known as GHSA-58p9-6mjq-rf2m.