CVE-2026-19574
HighCVSS 7.0Exploitation Probability (EPSS)
Low risk1th percentile - higher than 1% of all known CVEs
Summary
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.
Risk Assessment
The vulnerability allows bypassing the memory-domain isolation boundary and accessing another domain's partitions and thread stacks, potentially leading to data leakage or privilege escalation. It requires a CONFIG_USERSPACE application on ARM64 that creates more than 255 memory domains over its lifetime, and k_mem_domain_init() and k_mem_domain_deinit() are supervisor-only APIs not exposed as syscalls.
Recommendation
Update Zephyr RTOS to a version containing the fix that scans the live domain list before assigning an ASID, advances the round-robin counter past ASIDs already in use, and returns -ENOMEM when all are taken. Until patched, limit memory domain creation in CONFIG_USERSPACE applications on ARM64 to fewer than 255 over the system lifetime.
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-2026-19569High
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).
- CVE-2026-16513High
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.
Original NVD description (English source)
The ARM64 MMU back-end allocated address space identifiers (ASIDs) for memory domains with a bare round-robin counter in arch_mem_domain_init() (arch/arm64/core/mmu.c). VM_ASID_BITS is 8, so only 255 ASIDs exist; once the counter wrapped, arch_mem_domain_init() could hand an ASID to a new domain while a still-live domain held the same one. Domain-private mappings are installed non-global (MT_NG), so the ASID is the only tag separating one domain's cached translations from another's in the TLB. The context-switch path in z_arm64_swap_ptables() only flushes the TLB when the outgoing and incoming domains carry the same ASID, which does not cover a duplicate reached through a third domain: for domains A and C sharing an ASID and an unrelated domain B, the schedule A -> B -> C never takes the flush branch, so the ASID-tagged entries A populated remain resident while C runs. Under SMP two live domains sharing an ASID can additionally be resident on two CPUs at once, which the architecture does not allow for distinct translation-table sets. Triggering the wrap requires a CONFIG_USERSPACE application on ARM64 that creates more than 255 memory domains over its lifetime; k_mem_domain_init() and k_mem_domain_deinit() are supervisor-only APIs and are not exposed as syscalls, so an unprivileged thread cannot drive the counter directly. Once two live domains alias, however, a user-mode thread in one domain can read and write memory belonging to the other domain's partitions and thread stacks with that domain's permissions, defeating the memory-domain isolation boundary. The fix scans the live domain_list before assigning an ASID, advances the round-robin counter past ASIDs already in use, and returns -ENOMEM when all are taken, so domain creation fails closed instead of silently aliasing.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS