# CVE-2026-19575: Type confusion in the device_deinit system call allows user-mode threads to execute arbitrary kernel code > A type confusion in the device_deinit system call allows local unprivileged threads to execute arbitrary kernel code, bypassing userspace isolation. - **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Local or same network only - **Victim action needed:** Not needed - **Fix available:** No - **Published:** 9 Oct 2026 - **Updated:** 9 Oct 2026 - **Also known as:** GHSA-j9m4-fr5f-49wm ## What is CVE-2026-19575? CVE-2026-19575 is a high-severity code injection vulnerability in zephyrproject zephyr, published on 9 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim. ### Official description The user-mode verification handler for the device_deinit() system call, z_vrfy_device_deinit() in kernel/device.c, validated its dev argument with K_SYSCALL_OBJ_INIT(dev, K_OBJ_ANY). k_object_validate() short-circuits its type comparison when the requested type is K_OBJ_ANY, so the check reduced to "this pointer is the base address of some kernel object the calling thread has been granted" — the object's actual type was never compared, and K_SYSCALL_OBJ_INIT also skips the initialization-state check. The sibling handlers z_vrfy_device_init() and z_vrfy_device_is_ready() already used K_OBJ_DRIVER_ANY and were unaffected. A thread running in user mode can therefore pass any kernel object it holds permission on — most usefully a thread stack object obtained from the k_thread_stack_alloc() syscall or a statically defined K_THREAD_STACK it was granted in order to spawn a child user thread — whose backing memory is writable from user mode. z_impl_device_deinit() then interprets those attacker-written bytes as a struct device: it dereferences the state pointer read out of the object, calls the function pointer read out of ops.deinit, and on success writes through state again. The result is an indirect call to an arbitrary address executed in supervisor mode, plus an arbitrary kernel read and a single-byte kernel write. Exploitation gives a local unprivileged thread full kernel code execution, defeating the CONFIG_USERSPACE isolation boundary entirely; a less precise attempt yields a supervisor-mode fault and a system crash. The defect is only reachable in builds that enable both CONFIG_USERSPACE and CONFIG_DEVICE_DEINIT_SUPPORT — with de-initialization support disabled, z_impl_device_deinit() returns -ENOTSUP without ever dereferencing the pointer. In v4.2.x and v4.3.x, CONFIG_DEVICE_DEINIT_SUPPORT defaulted to y, so every CONFIG_USERSPACE build of those releases is exposed unless the option was explicitly turned off. From v4.4.0 the option is opt-in (no default, and not selected by any in-tree subsystem), so a v4.4.x build is exposed only if it enables the option explicitly. The v4.2 line is no longer maintained and receives no backport. The fix changes the object check to K_OBJ_DRIVER_ANY, which constrains the argument to the build-generated driver object type range (K_OBJ_DRIVER_FIRST..K_OBJ_DRIVER_LAST) — the real struct device instances placed by the linker — so the state and ops.deinit fields are once again kernel-controlled. Weakness: CWE-843 (Access of Resource Using Incompatible Type) ## Which versions are affected by CVE-2026-19575? ## How do I fix CVE-2026-19575? No fix has been published for CVE-2026-19575 yet. Limit exposure of the affected software until one is available. ## Is CVE-2026-19575 being exploited? There is no known exploitation of CVE-2026-19575 in the wild and no public exploit code. ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-19575 and fix it if it is affected. What it is: CVE-2026-19575 is a high-severity code injection vulnerability in zephyrproject zephyr, published on 9 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2026-19575 in the wild and no public exploit code. Affected product: zephyrproject zephyr. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-19575/ (Markdown: https://insights.sbomify.com/CVE-2026-19575/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-19575 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-19575 - OSV: https://osv.dev/vulnerability/CVE-2026-19575 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-19575/ Summaries are generated and may contain mistakes; the official description above is the record.