Live › vulnerability › CVE-2026-19676
Go to dashboardThe PECI transfer system call in Zephyr does not check the buffer pointers and lengths inside its message struct, so a user-mode thread holding the PECI device can point them at kernel memory. An attacker can write hardware-supplied bytes into kernel memory for code execution at supervisor privilege, or read kernel data out over the PECI bus.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-23 21:57 UTC. All times on this page are UTC.
Zephyr applications that run user-mode threads (CONFIG_USERSPACE) and that grant those threads access to a PECI device using one of the in-tree PECI drivers for NPCX, XEC or IT8XXX2 hardware. Systems without userspace or without these PECI drivers do not have this exposure, and single-privilege firmware with no user threads can skip it.
No product ranges from the sources yet.
CONFIG_USERSPACE=y and enables one of CONFIG_PECI_NPCX, CONFIG_PECI_XEC or CONFIG_PECI_ITE_IT8XXX2git describe --tags and compare it with the fixed release in the advisory (unknown in sources)K_SYSCALL_MEMORY_READ() and K_SYSCALL_MEMORY_WRITE() checks in drivers/peci/peci_handlers.c (fixed version: unknown in sources)CONFIG_USERSPACE for affected buildsEach row is the first time that source carried this signal. The analyst’s rows are its own findings.
The user-mode verifier for the peci_transfer() system call, z_vrfy_peci_transfer() in drivers/peci/peci_handlers.c, checked only the device object permission and copied the caller-supplied struct peci_msg with k_usermode_from_copy(). That copy validates the outer structure only; the buf pointers and len values inside the embedded struct peci_buf members tx_buffer and rx_buffer remained fully caller-controlled and were passed unchecked to the driver.
Every in-tree PECI driver dereferences those pointers in supervisor mode: peci_npcx_transfer() in drivers/peci/peci_npcx.c and peci_it8xxx2_transfer() in drivers/peci/peci_ite_it8xxx2.c copy hardware bytes into rx_buffer.buf[i] and read command bytes out of tx_buffer.buf[i], and peci_xec_read()/peci_xec_write() in drivers/peci/peci_mchp_xec.c do the same with no bound on rx_buffer.len at all. A user-mode thread that has been granted the PECI device object — the normal way an application exposes a device under CONFIG_USERSPACE — could therefore point rx_buffer.buf at kernel data structures and have the driver write hardware-supplied bytes there, or point tx_buffer.buf at kernel memory and have its contents pushed onto the PECI/eSPI out-of-band bus.
The impact is a full user-mode-to-kernel escape: an arbitrary kernel write primitive (integrity and, through it, code execution at supervisor privilege), an arbitrary kernel read disclosed to a PECI bus observer, and a trivially reachable supervisor-mode fault if an unmapped address is supplied. Exploitation requires CONFIG_USERSPACE=y, one of the PECI drivers enabled (CONFIG_PECI_NPCX, CONFIG_PECI_XEC or CONFIG_PECI_ITE_IT8XXX2), and local code execution in a user-mode thread holding the PECI device.
The fix adds K_SYSCALL_MEMORY_READ() and K_SYSCALL_MEMORY_WRITE() checks over the two embedded buffers, with a size_add_overflow() guard on the frame-check-sequence byte accounted for in the RX length.
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