zephyrproject zephyr up to 4.4.x Userspace Verification kernel/thread.c z_vrfy_k_thread_name_copy thread null pointer dereference

Summaryinfo

A vulnerability was found in zephyrproject zephyr up to 4.4.x. It has been declared as problematic. This affects the function z_vrfy_k_thread_name_copy of the file kernel/thread.c of the component Userspace Verification Handler. Such manipulation of the argument thread leads to null pointer dereference. This vulnerability is traded as CVE-2026-10670. An attack has to be approached locally. There is no exploit available.

Detailsinfo

A vulnerability was found in zephyrproject zephyr up to 4.4.x. It has been rated as problematic. Affected by this issue is the function z_vrfy_k_thread_name_copy of the file kernel/thread.c of the component Userspace Verification Handler. The manipulation of the argument thread with an unknown input leads to a null pointer dereference vulnerability. Using CWE to declare the problem leads to CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Impacted is availability. CVE summarizes:

The CONFIG_USERSPACE verification handler for the k_thread_name_copy() system call (z_vrfy_k_thread_name_copy() in kernel/thread.c) calls k_object_find() on the caller-supplied thread pointer and then dereferences the returned struct k_object without checking it for NULL. k_object_find() returns NULL whenever the supplied pointer is not a registered (static or dynamic) kernel object. The pre-fix guard tested thread == NULL instead of ko == NULL, so an unprivileged user-mode thread that invokes k_thread_name_copy() with any non-NULL but unregistered pointer (e.g. an arbitrary address) passes the NULL test, after which the verifier reads ko->type through a NULL pointer. Because the syscall verifier runs in supervisor mode, this NULL dereference is a kernel-mode fault that halts or reboots the system, allowing untrusted user code to crash the kernel across the userspace security boundary (denial of service). The marshaller passes the thread argument to the verifier without any prior K_SYSCALL_OBJ validation, so the bad pointer reaches the defect directly. The flaw affects builds with CONFIG_USERSPACE and CONFIG_THREAD_NAME enabled and has been present since the special-case lookup was introduced around v2.0.0; it is present in v4.4.0 and earlier. The fix changes the guard to check the k_object_find() return value (ko == NULL) before dereferencing it.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-10670 since 06/02/2026. The exploitation is known to be easy. Local access is required to approach this attack. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit.

Upgrading to version 4.5.0 eliminates this vulnerability.

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Productinfo

Type

• Project Management Software

Vendor

• zephyrproject

Name

• zephyr

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4

CPE 2.3info

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CPE 2.2info

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