{"id":"CVE-2026-19676","summary":"PECI transfer syscall verifier does not validate embedded user buffer pointers, allowing arbitrary kernel memory read/write from user mode","details":"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.","aliases":["GHSA-g66q-frxm-3hfg"],"modified":"2026-10-22T07:28:28.022671612Z","published":"2026-10-21T18:19:27.767Z","database_specific":{"cna_assigner":"zephyr","cwe_ids":["CWE-822"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/19xxx/CVE-2026-19676.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/19xxx/CVE-2026-19676.json"},{"type":"PACKAGE","url":"https://github.com/zephyrproject-rtos/zephyr"},{"type":"FIX","url":"https://github.com/zephyrproject-rtos/zephyr/commit/d7faf323d52b7e8845a63b1f854a82bdda44c261"},{"type":"ADVISORY","url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-g66q-frxm-3hfg"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-19676"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/zephyrproject-rtos/zephyr","events":[{"introduced":"b8c78e254ff875680e99c9f131fbe285c4575927"},{"last_affected":"dccb09599635bdff17633fa7e9dab014b91dce90"},{"fixed":"d7faf323d52b7e8845a63b1f854a82bdda44c261"}],"database_specific":{"extracted_events":[{"range":[{"introduced":"2.3.0"},{"last_affected":"4.4.2"}],"source":"AFFECTED_FIELD","strategy":"StandardRange"},{"range":[{"fixed":"d7faf323d52b7e8845a63b1f854a82bdda44c261"}],"source":"REFERENCES_COMMIT"}]}}],"versions":["v4.4.2","v4.4.2-rc1","v4.4.1","v4.4.1-rc1","v4.4.0","v4.4.0-rc3","v4.4.0-rc2","v4.4.0-rc1","v4.3.0","v4.3.0-rc3","v4.3.0-rc2","v4.3.0-rc1","v4.2.0","v4.2.0-rc3","v4.2.0-rc2","v4.2.0-rc1","v4.1.0","v4.1.0-rc3","v4.1.0-rc2","v4.1.0-rc1","v4.0.0","v4.0.0-rc3","v4.0.0-rc2","v4.0.0-rc1","v3.7.0","v3.7.0-rc3","v3.7.0-rc2","v3.7.0-rc1","v3.6.0","v3.6.0-rc3","v3.6.0-rc2","v3.6.0-rc1","zephyr-v3.5.0","v3.5.0","v3.5.0-rc3","v3.5.0-rc2","v3.5.0-rc1","zephyr-v3.4.0","v3.4.0","v3.4.0-rc3","v3.4.0-rc2","v3.4.0-rc1","zephyr-v3.3.0","v3.3.0","v3.3.0-rc3","v3.3.0-rc2","v3.3.0-rc1","zephyr-v3.2.0","v3.2.0","v3.2.0-rc3","v3.2.0-rc2","v3.2.0-rc1","zephyr-v3.1.0","v3.1.0","v3.1.0-rc3","v3.1.0-rc2","v3.1.0-rc1","zephyr-v3.0.0","v3.0.0","v3.0.0-rc3","v3.0.0-rc2","v3.0.0-rc1","v2.7.99","v2.7.0-rc3","v2.7.0-rc2","v2.7.0-rc1","zephyr-v2.6.0","v2.6.0","v2.6.0-rc3","v2.6.0-rc2","v2.6.0-rc1","zephyr-v2.5.0","v2.5.0","v2.5.0-rc4","v2.5.0-rc3","v2.5.0-rc2","v2.5.0-rc1","zephyr-v2.4.0","v2.4.0","v2.4.0-rc3","v2.4.0-rc2","v2.4.0-rc1","zephyr-v2.3.0","v2.3.0"],"database_specific":{"vanir_signatures":[{"signature_version":"v1","source":"https://github.com/zephyrproject-rtos/zephyr/commit/d7faf323d52b7e8845a63b1f854a82bdda44c261","target":{"file":"drivers/peci/peci_handlers.c"},"deprecated":false,"digest":{"threshold":0.9,"line_hashes":["193817567228127920469200340415201109375","299647773395740300829229593761069990325","136072482116092086039328699603181677520"]},"id":"CVE-2026-19676-22ae1fbd","signature_type":"Line"},{"target":{"function":"z_vrfy_peci_transfer","file":"drivers/peci/peci_handlers.c"},"deprecated":false,"digest":{"function_hash":"90785820985704767109937369812603996206","length":228},"id":"CVE-2026-19676-b8f71b73","signature_type":"Function","signature_version":"v1","source":"https://github.com/zephyrproject-rtos/zephyr/commit/d7faf323d52b7e8845a63b1f854a82bdda44c261"}],"vanir_signatures_modified":"2026-10-22T07:28:28Z","source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-19676.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}