NULL pointer dereference in USB DFU device_next download handler (handle_download)

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-12051
StatePUBLISHED
Assignerzephyr
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-11 06:17:12 UTC
Updated2026-08-11 06:17:12 UTC
DescriptionThe 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.

Risk And Classification

Primary CVSS: v3.1 4.6 MEDIUM from [email protected]

CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-476 | CWE-476 memory-safety

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.6MEDIUMCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
3.1CNACVSS4.6MEDIUMCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Physical
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Zephyrproject Zephyr affected 4.4.0 4.5.0 semver Not specified

References

ReferenceSourceLinkTags
github.com/zephyrproject-rtos/zephyr/commit/552ca371257597b71490482d5cc5... [email protected] github.com
github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-vhvq-q6rw-... [email protected] github.com
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