CVE-2026-16513
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk6th percentile - higher than 6% of all known CVEs
Summary
A vulnerability in the RTIO syscall verifier in Zephyr RTOS (before v4.3.0) allows an unprivileged user thread to write a pointer to controlled data at an arbitrary kernel address. The missing K_SYSCALL_MEMORY_WRITE check for the handle output parameter enables privilege escalation to kernel mode.
Risk Assessment
An attacker can overwrite kernel function pointers, thread structures, or memory domain partition tables, leading to full system compromise or crash. This breaks the isolation provided by CONFIG_USERSPACE.
Recommendation
Update Zephyr RTOS to version 4.3.0 or later, which includes the fix adding write validation for the handle parameter. If updating is not possible, restrict access to RTIO objects to trusted threads only.
Other vulnerabilities in Zephyr RTOS
See all- CVE-2026-82962Medium
A vulnerability in ethernet_fill_header() in the Zephyr RTOS network stack prepends the Ethernet header in place via net_buf_push without verifying that the packet has sufficient headroom. Packets allocated by a different L2 (e.g., 802.15.4/OpenThread, PPP) and handed to Ethernet through routing or tunnelling have too little (usually zero) headroom, causing an out-of-bounds write. In builds without CONFIG_ASSERT and CONFIG_NET_BUF_HARDENING this results in memory corruption.
- CVE-2026-19595Medium
A vulnerability in the Zephyr RTOS syscall verifier: z_vrfy_rtio_cqe_get_mempool_buffer() validated its output parameters buff and buff_len with K_SYSCALL_MEMORY_READ() instead of K_SYSCALL_MEMORY_WRITE(). This allows an unprivileged user-mode thread to invoke the syscall with pointers to read-only memory, causing a supervisor-mode store outside the permitted region or a kernel fault that halts or reboots the device.
- CVE-2026-19940Medium
A vulnerability in the Bluetooth Classic Hands-Free Profile Audio Gateway (HFP AG) implementation in Zephyr RTOS causes corruption of the kernel timeout list. By sending AT+CIND? and quickly reconnecting, a remote attacker can trigger a system-wide fault or hang.
- CVE-2026-19736High
The NXP MCUX TRNG entropy driver in Zephyr (drivers/entropy/entropy_mcux_trng.c) passes the caller's byte count directly to the SDK routine TRNG_GetRandomData(), which on i.MX RT5xx/RT6xx parts always copies whole 32-bit words and rounds entropy draws up to a multiple of 128 bytes. A request length not a multiple of four causes an underflow in the SDK's buffer-full check, leading to an overflow of up to 127 bytes past the caller's buffer.
- CVE-2026-19575High
A vulnerability in Zephyr RTOS affects the user-mode verification handler z_vrfy_device_deinit() in kernel/device.c, which validated its dev argument with K_SYSCALL_OBJ_INIT(dev, K_OBJ_ANY). Because k_object_validate() short-circuits type comparison for K_OBJ_ANY, the check only verified that the pointer was the base address of some kernel object the calling thread was granted, without comparing the object's actual type. This allows a local user-mode thread to pass a thread stack object (e.g., from k_thread_stack_alloc()) and achieve supervisor-mode kernel code execution.
- CVE-2026-19574High
In the ARM64 MMU back-end of Zephyr RTOS, address space identifiers (ASIDs) are assigned by a bare round-robin counter, which after wrapping past 255 possible values can hand the same ASID to a new domain while a still-live domain holds it. Because domain-private mappings are installed as non-global (MT_NG), the ASID is the only tag separating cached translations in the TLB, and the context-switch path does not flush the TLB for a duplicate reached through a third domain. As a result, user-mode threads in one domain can read and write memory belonging to another domain, defeating memory-domain isolation.
- CVE-2026-19569High
A vulnerability in the Zephyr RTOS kernel allows an unprivileged user-mode thread to perform an out-of-bounds write in kernel memory. It stems from missing overflow checks when calculating allocation sizes for dynamic kernel objects, leading to undersized heap allocations. An attacker can exploit this to escalate privileges and execute arbitrary code at the kernel level.
- CVE-2026-19185High
A vulnerability was found in the system-call verifier for i3c_do_ccc() in Zephyr RTOS, which fails to validate per-target data pointers in the i3c_ccc_payload structure. The verifier also operates on the caller's live structure, allowing another thread to modify fields between check and use. This allows an unprivileged thread to write to arbitrary kernel addresses (via read CCC) or disclose kernel memory (via write CCC), leading to privilege escalation.
- CVE-2026-18747Medium
A vulnerability in the SMP-over-console transport in Zephyr RTOS allows an unauthenticated attacker to trigger a buffer length underflow by sending a single 7-byte frame to the management console. This leads to an out-of-bounds read, potentially causing a denial of service on the MCUmgr thread or memory disclosure.
- CVE-2026-18417Medium
In Zephyr RTOS, a vulnerability exists in the BSD socket layer where an asynchronous error was stored in the user_data field of the network context, which for listening TCP sockets is used to store a pointer to the parent context. In v4.3.0, after an interface-down event, the accept callback was not disarmed, leading to reuse of the poisoned value as a pointer and writes to an invalid address, causing a kernel fatal error (device crash or reset).
Original NVD description (English source)
The userspace verifier z_vrfy_rtio_sqe_copy_in_get_handles() in subsys/rtio/rtio_syscalls.c (subsys/rtio/rtio_handlers.c before v4.3.0) validated the RTIO object handle and the sqes input array, but not the handle out-parameter. On the first loop iteration it executed *handle = sqe, storing the kernel address of the newly acquired submission-queue entry through a pointer taken verbatim from user mode, with no K_SYSCALL_MEMORY_WRITE check in front of it. Any user-mode thread that has been granted a struct rtio kernel object can invoke the syscall with an arbitrary address in handle. That is the ordinary way an unprivileged thread uses the RTIO API, for example via sensor_read_async_mempool() or the async ADC helpers, which call rtio_sqe_copy_in_get_handles() internally. The store happens in supervisor mode before any submission-entry validation, so it fires regardless of whether the SQE contents are subsequently rejected. Only builds with CONFIG_USERSPACE and CONFIG_RTIO are affected; without CONFIG_USERSPACE the verifier is not compiled and the caller is already privileged. The write address is fully attacker-chosen and the written value is a pointer into the caller's own RTIO ring, whose contents the caller controls (the following *sqe = sqes[i] copies an attacker-supplied struct rtio_sqe into that slot). This yields a write-what-where primitive placing a pointer to attacker-controlled data at any kernel address, sufficient to corrupt kernel function pointers, thread structures, or memory-domain partition tables, and thus to escalate from user mode to kernel mode, defeating the isolation boundary CONFIG_USERSPACE is meant to enforce. At minimum it is a reliable kernel memory-corruption and crash primitive. The reporter reproduced the write on qemu_x86: a K_USER thread changed a supervisor global from NULL to a live kernel SQE pointer. The fix adds K_SYSCALL_MEMORY_WRITE(handle, sizeof(*handle)) (guarded by the existing optional-NULL semantics) before the loop, so the destination must lie in the calling thread's writable memory domain or the thread is terminated by K_OOPS. The neighbouring verifier z_vrfy_rtio_cqe_get_mempool_buffer(), which checked its buff/buff_len out-parameters only for read although the implementation writes through them, was hardened separately by bea93400138 ("rtio: syscalls: validate output params as writable"); that residual was materially weaker, since a read check still confines the target to the caller's own memory domain.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS