{"id":"CVE-2026-9771","summary":"Missing device-pointer validation in flash_copy() syscall allows userspace privilege escalation","details":"The flash_copy() system call is verified by z_vrfy_flash_copy() in drivers/flash/flash_util.c. On builds with CONFIG_USERSPACE enabled, this handler is the kernel-side trust boundary for a user-mode caller. Prior to the fix it validated only the output buffer (K_SYSCALL_MEMORY_WRITE) and passed the two struct device * arguments, src_dev and dst_dev, directly into the implementation without any object validation — unlike every sibling flash syscall, which guards its device pointer with K_SYSCALL_DRIVER_FLASH.\n\nA user-mode thread fully controls the values of src_dev/dst_dev and the contents of its own address space. The implementation z_impl_flash_copy() dereferences these pointers and calls through their driver-API function tables (e.g. api-\u003eget_parameters(dst_dev), flash_read(src_dev, ...), flash_write(dst_dev, ...)). By supplying a pointer to a forged struct device whose api table contains attacker-chosen function pointers, an unprivileged thread can cause the kernel to call arbitrary code in supervisor mode; passing any arbitrary or invalid address otherwise yields a kernel crash or out-of-bounds read.\n\nThe result is a local privilege escalation out of the userspace sandbox (with kernel denial-of-service and information disclosure as lesser outcomes). The fix adds K_SYSCALL_DRIVER_FLASH(src_dev, read) and K_SYSCALL_DRIVER_FLASH(dst_dev, write) to z_vrfy_flash_copy(), which verify each device is a registered flash-driver kernel object the calling thread is permitted to use before any dereference, closing the path completely.","aliases":["GHSA-68cj-3hg4-5vpm"],"modified":"2026-08-28T14:32:44.391646Z","published":"2026-08-17T16:18:52.514Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/9xxx/CVE-2026-9771.json","cna_assigner":"zephyr","cwe_ids":["CWE-822","CWE-862"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/9xxx/CVE-2026-9771.json"},{"type":"ADVISORY","url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-68cj-3hg4-5vpm"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-9771"},{"type":"FIX","url":"https://github.com/zephyrproject-rtos/zephyr/commit/1b1ecdc438092cdd469319a0d51cba6cf82e06f4"},{"type":"PACKAGE","url":"https://github.com/zephyrproject-rtos/zephyr"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/zephyrproject-rtos/zephyr","events":[{"introduced":"8469084dfae85f854555f0607f2c838dad097235"},{"fixed":"1b1ecdc438092cdd469319a0d51cba6cf82e06f4"}],"database_specific":{"extracted_events":[{"introduced":"4.0.0"},{"fixed":"4.4.2"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["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"],"database_specific":{"vanir_signatures":[{"target":{"file":"drivers/flash/flash_util.c","function":"z_vrfy_flash_copy"},"deprecated":false,"digest":{"function_hash":"100892125198567856689040843167104803490","length":254},"id":"CVE-2026-9771-1c6c4924","signature_type":"Function","signature_version":"v1","source":"https://github.com/zephyrproject-rtos/zephyr/commit/1b1ecdc438092cdd469319a0d51cba6cf82e06f4"},{"id":"CVE-2026-9771-688d4e39","signature_type":"Line","signature_version":"v1","source":"https://github.com/zephyrproject-rtos/zephyr/commit/1b1ecdc438092cdd469319a0d51cba6cf82e06f4","target":{"file":"drivers/flash/flash_util.c"},"deprecated":false,"digest":{"line_hashes":["276261383087426832510780906243271212172","284927988519439152428083085732407973644","167297332171150506350564659460081924575","327906297799209277174700094083138468705"],"threshold":0.9}}],"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-9771.json","vanir_signatures_modified":"2026-08-28T14:32:44Z"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"}]}