{"id":"CVE-2026-19676","revision":null,"records":[{"revision":"8204e53c15824701a9709c73cf5b09bf","observedAt":"2026-10-23T22:48:20.692+00:00","statement":{"source":"cve-program","id":"CVE-2026-19676","aliases":[],"title":"PECI transfer syscall verifier does not validate embedded user buffer pointers, allowing arbitrary kernel memory read/write from user mode","description":"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.\n\nEvery 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.\n\nThe 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.\n\nThe 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.","state":0,"publishedAt":"2026-10-21T18:19:27.767+00:00","modifiedAt":"2026-10-23T21:57:28.879+00:00","affected":[{"ecosystem":"https://github.com/zephyrproject-rtos/zephyr","name":"zephyr","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"zephyrproject\",\n                    \"product\": \"zephyr\",\n                    \"collectionURL\": \"https://github.com/zephyrproject-rtos/zephyr\",\n                    \"packageName\": \"zephyr\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"programFiles\": [\n                        \"drivers/peci/peci_handlers.c\"\n                    ],\n                    \"programRoutines\": [\n                        {\n                            \"name\": \"z_vrfy_peci_transfer\"\n                        }\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"2.3.0\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\",\n                            \"lessThanOrEqual\": \"4.4.2\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://github.com/zephyrproject-rtos/zephyr/commit/d7faf323d52b7e8845a63b1f854a82bdda44c261","https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-g66q-frxm-3hfg"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-19676","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-19676","identifiers":["CVE-2026-19676"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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