Zephyr Project up to 4.4.2 PECI peci_handlers.c z_vrfy_peci_transfer len privileges management

Summaryinfo

A vulnerability labeled as very critical has been found in Zephyr Project Zephyr up to 4.4.2. This vulnerability affects the function z_vrfy_peci_transfer of the file drivers/peci/peci_handlers.c of the component PECI. Executing a manipulation of the argument len can lead to privileges management. This vulnerability is handled as CVE-2026-19676. It is possible to launch the attack on the local host. There is not any exploit available. It is best practice to apply a patch to resolve this issue.

Detailsinfo

A vulnerability has been found in Zephyr Project Zephyr up to 4.4.2 and classified as very critical. This vulnerability affects the function z_vrfy_peci_transfer of the file drivers/peci/peci_handlers.c of the component PECI. The manipulation of the argument len with an unknown input leads to a privileges management vulnerability. The CWE definition for the vulnerability is CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability was named CVE-2026-19676 since 08/13/2026. The exploitation appears to be easy. Local access is required to approach this attack. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 10/21/2026). This vulnerability is assigned to T1068 by the MITRE ATT&CK project.

Applying the patch d7faf323d52b7e8845a63b1f854a82bdda44c261 is able to eliminate this problem.

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Productinfo

Type

• Project Management Software

Vendor

• Zephyr Project

Name

• Zephyr

Version

• 4.4.0
• 4.4.1
• 4.4.2

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CPE 2.2info

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