CVE-2026-90587zephyrproject zephyr null pointer dereference
CVE-2026-90587 is a null pointer dereference in zephyrproject zephyr, rated medium (4.6 on CVSS 3.1).
Why this priority: Medium severity, with no exploitation signal.
Published · Updated · NVD status: Awaiting Analysis
What it is
Code uses a null pointer and crashes, usually taking the service down.
How it is reached
An attacker can exploit it with physical access to the device, without an account, and nobody has to click anything.
What an attacker gains
A successful attack can take it offline. In practice, this kind of flaw lets an attacker crash the process, read memory, or in the worst case run code.
Is it being exploited?
There is no public report of exploitation yet.
What to do
- Upgrade zephyrproject zephyr to 4.5.0 or later.
Description from NVD
usbh_device_init() in subsys/usb/host/usbh_device.c rejects a device whose device descriptor advertises bNumConfigurations == 0, but it only logs the error and jumps to the cleanup label without setting the return code. At that point the local err is still 0 from the preceding successful descriptor read, so the function returns success while having skipped usbh_device_set_configuration() — the only place udev->cfg_desc is allocated. The device structure is zero-initialised by usbh_device_alloc(), so udev->cfg_desc remains NULL.
usbh_device_connect() treats the zero return as a successful enumeration and calls usbh_class_probe_device(), which starts its descriptor walk from udev->cfg_desc. usbh_desc_get_next_function() passes that NULL pointer to usbh_desc_is_valid(), whose only guard compares the caller-supplied size, so head->bLength is read through a NULL pointer.
The condition is triggered entirely by the attached peripheral: attaching a USB device (or any USB gadget emulating one) that reports bNumConfigurations = 0 reaches the defect directly from the UHC_EVT_DEV_CONNECTED_FS/_HS event handler in subsys/usb/host/usbh_core.c, with no authentication and no user interaction beyond the physical attachment.
On targets where page zero is unmapped or CONFIG_NULL_POINTER_EXCEPTION_DETECTION is enabled this raises a fatal exception in the USB host thread, denying service to the host. Where address zero is readable, the descriptor walker instead parses low memory as a descriptor chain and can dispatch a class probe() with attacker-influenced values, causing further out-of-bounds reads through the still-NULL udev->cfg_desc in usbh_desc_get_iface(). No attacker-controlled write was identified, so the impact is availability plus a bounded out-of-bounds read. Note that CONFIG_USB_HOST_STACK is marked experimental.
What this means for your architecture.
A CVE names a product. Whether it matters depends on where that product sits in your systems: what reaches it, which trust boundary it guards and what it can reach once compromised. Veriom maps your components, their relationships and your trust boundaries from your code, cloud and delivery evidence, so you can see where a component like this sits. The radar itself does not look at your systems.
Components it touches
- Native code: operating systems, browsers and firmware. The flaw sits wherever native code reads untrusted data.
- Network appliances and media or file parsers. The flaw sits wherever native code reads untrusted data.
Trust boundaries in play
- Host boundary. The attacker needs a foothold on the machine first; the flaw turns a small foothold into a bigger one.
- Wherever native code reads untrusted data. An attacker who crosses it can crash the process, read memory, or in the worst case run code.
Questions to answer about your own systems
- Where does zephyrproject zephyr run in your systems, and at which version?
- Which of those devices sit where outsiders can touch them?
- What can it reach once compromised: which data stores, secrets and services?
Sources
- CVE records and CVSS scores from the NVD CVE API. This product uses the NVD API but is not endorsed or certified by the NVD.
- Exploitation status from CISA’s Known Exploited Vulnerabilities catalog.
- Exploit likelihood from FIRST’s Exploit Prediction Scoring System (EPSS), refreshed daily.
- Explanations are written by Veriom from fixed templates over each record’s data, not by a person reviewing each CVE. Descriptions are quoted from the records as published.