Highly exploitable, CVE-2026-19575 poses a critical security risk that could lead to severe breaches.
Status: Received on 09 Oct 2026, 08:16 UTC
Published on: 09 Oct 2026, 08:16 UTC
CVSS Release: version 3
vulnerabilities@zephyrproject.org
Secondary
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVE-2026-19575: 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 The v4.2 line is no longer maintained and receives no backport.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.
The exploitability of CVE-2026-19575 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
CVE-2026-19575 presents an accessible attack vector with minimal effort required. Restricting access controls and implementing security updates are critical to reducing exploitation risks.
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
Above is the CVSS Sub-score Breakdown for CVE-2026-19575, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
Below is the Impact Analysis for CVE-2026-19575, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
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