NULL pointer dereference in USB DFU device_next download handler (handle_download)
Key facts
- Attack vector
- Physical
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-476.
Summary
The USB DFU class implementation in Zephyr's new (experimental) device_next USB device stack contains a NULL pointer dereference in handle_download() (subsys/usb/device_next/class/usbd_dfu.c). The handler computes MIN(setup->wLength, buf->len) and passes buf->data to the image write callback without checking that the buf net_buf pointer is non-NULL. The handler is reached over the USB control endpoint, driven by the USB host. For a DFU_DNLOAD (download) request with no Data OUT stage — notably the zero-length terminating download that the DFU protocol uses to end a firmware transfer — the USB core invokes the class handler with a NULL buffer. After the device has been advanced to the DFU_DNLOAD_IDLE state (by sending one valid download block and a GET_STATUS), a zero-length DFU_DNLOAD reaches handle_download() with buf == NULL, dereferencing it. The result is a NULL+offset read that triggers a fatal CPU fault, i.e. a denial of service (device crash/reset). The attacker is whatever controls the USB host the device is attached to; DFU download support must be enabled with a registered image. There is no memory corruption or information disclosure — impact is limited to availability. The fix adds an explicit if (buf != NULL) guard so the callback receives a zero-length, NULL-data transfer instead of crashing.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| zephyrproject | zephyr | 4.4.0 to before 4.4.2 | 4.4.2 | Patch available | CNA |
- zephyr Vendorzephyrproject Affected 4.4.0 to before 4.4.2 Fixed in 4.4.2 Patch available CNA
CPE names Threatist (inferred) · 1
Inferred from how NVD named this product before; not given by a source.
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:zephyrproject:zephyr:*:*:*:*:*:*:*:* | — | — | zephyrproject |
- cpe:2.3:o:zephyrproject:zephyr:*:*:*:*:*:*:*:* Versions — — ·zephyrproject
Remediation
- Fix · CNA zephyr (zephyrproject) Fixed in 4.4.2
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
zephyrproject zephyr 4.4.2
4 records Highest priority Priority LOW 4 LOW
Other records, highest priority first
- TI-2026-10262 Double-free / use-after-free in Realtek BEE Bluetooth HCI driver `send()` error pathsPriority LOW 26
- TI-2026-10261 Double free / use-after-free in Bouffalo Lab HCI driver send() error paths (hci_bflb)Priority LOW 26
- TI-2026-10328 Cross-thread FPU register leak on ARM when FPU enabled without register sharingPriority LOW 16
Timeline
- 2026-10-02 Threatist record created from CVE-2026-12051
References
Patch 1
Other 1
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Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences