CVE-2026-19809zephyrproject zephyr use of uninitialized resource
CVE-2026-19809 is a use of uninitialized resource in zephyrproject zephyr, rated low (3.3 on CVSS 3.1).
Why this priority: Low severity, with no exploitation signal.
Published · Updated · NVD status: Awaiting Analysis
What it is
A resource is used before it is initialised, exposing leftover data.
How it is reached
An attacker can exploit it by someone who can already run code or sign in on the machine, with an ordinary user account, and nobody has to click anything.
What an attacker gains
The direct impact is limited: partial access to data or a partial outage. 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 a fixed version for your release line (4.3.2, 4.5.0).
- Limit who can run code or sign in on the hosts that run it.
Description from NVD
The user-mode system call verifier z_vrfy_charger_get_prop() in drivers/charger/charger_handlers.c declares an uninitialized union charger_propval k_val on the kernel (privileged) stack, passes it to the charger driver back end via z_impl_charger_get_prop(), and then copies the full sizeof(union charger_propval) back into the calling user thread's buffer with k_usermode_to_copy(). That discloses kernel stack contents on two paths:
On error. The copy-out ignores the driver's return code. In-tree back ends return an error without writing through the value pointer for properties they do not implement: charger_gpio_get_prop() returns -ENOTSUP unconditionally, and bq24190_get_prop() has a default: return -ENOTSUP; arm that never touches val. The whole union is then stack residue. On success. A back end writes only the one union member the requested property selects (for example sbs_charger.c writes the one-byte val->present for CHARGER_PROP_PRESENT and returns 0), yet the handler still copies the whole union, so every byte beyond that member is uninitialized.
The handler is compiled only when CONFIG_USERSPACE=y and is reachable by any user-mode thread that has been granted access to a charger device object. K_SYSCALL_DRIVER_CHARGER() validates only the device object and its API pointer, not the property identifier, so an unprivileged thread can choose prop freely: an unimplemented property forces the error path, a narrow one the success path, and the call can be repeated at will.
Each call discloses up to the size of the union (12 bytes on a 32-bit target, 16 bytes on 64-bit targets where the function-pointer members widen it) of supervisor-stack memory. The bytes are residue of earlier kernel-side frames on the thread's privileged stack and can contain kernel object addresses and saved return addresses, which an unprivileged thread cannot otherwise observe and which help defeat address-layout assumptions when exploiting a separate memory-safety defect. There is no integrity or availability impact.
Two commits fix it, and both are needed. 5054384e983c skips the copy-out when the back end reports an error. c31cac727d02 zeroes the union before the driver call, so the bytes copied out on success are driver-written data or zeros. A tree carrying only the first still leaks on every successful call.
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 hosts also run code or users you do not fully trust?
- 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.