{"api_version":"1","generated_at":"2026-10-29T18:15:56+00:00","cve":"CVE-2026-19595","urls":{"html":"https://cve.report/CVE-2026-19595","api":"https://cve.report/api/cve/CVE-2026-19595.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-19595","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-19595"},"summary":{"title":"Zephyr RTIO syscall verifier validates output parameters for read instead of write access","description":"The user-mode syscall verifier z_vrfy_rtio_cqe_get_mempool_buffer() in subsys/rtio/rtio_syscalls.c validated its two output parameters, buff and buff_len, with K_SYSCALL_MEMORY_READ() rather than K_SYSCALL_MEMORY_WRITE(). Both are pure out-parameters: z_impl_rtio_cqe_get_mempool_buffer() stores the mempool buffer address and its length through them. The distinction is enforced by every architecture validator — arch_buffer_validate() on RISC-V PMP explicitly accepts the global __rom_region/__rodata_region for reads only, and the ARM MPU validators accept P_RO_U_RO and P_RW_U_RO regions for reads only — so a read-validated pointer is not necessarily writable by the calling thread.\n\nAn unprivileged user-mode thread that has been granted access to an RTIO context (rtio_access_grant()) can invoke the rtio_cqe_get_mempool_buffer() syscall with buff/buff_len pointing at memory it may read but not write, and with a completion-queue entry whose flags field it fully controls (only RTIO_CQE_FLAG_MEMPOOL_BUFFER in flags[7:0] is required; flags[19:8] and flags[31:20] supply the block index and count). The kernel then performs a pointer-sized and a 4-byte store through those addresses while running in supervisor mode. Reaching the store requires CONFIG_USERSPACE together with CONFIG_RTIO_SYS_MEM_BLOCKS, the configuration behind RTIO_DEFINE_WITH_MEMPOOL; without the latter the implementation returns -ENOTSUP and writes nothing.\n\nTwo outcomes follow. If the target lies in a memory-domain partition declared K_MEM_PARTITION_P_RW_U_RO (privileged read-write, user read-only), the kernel-mode store succeeds and deposits partly attacker-chosen values into memory the memory domain had marked read-only for that thread, bypassing the partition's write protection. If the target lies in globally readable but unwritable memory such as .text/.rodata in flash, the store faults in kernel mode; the fault is delivered to z_fatal_error() and the default k_sys_fatal_error_handler() halts or reboots the device, giving an unprivileged thread a reliable full denial of service.\n\nThe read-permission check does bound the damage: the address must still be readable by the calling thread, so kernel-private memory cannot be targeted and no confidential data is disclosed. The fix replaces both checks with K_SYSCALL_MEMORY_WRITE(), so a thread lacking write permission is terminated by K_OOPS before the implementation runs; the cqe argument correctly remains read-validated.","state":"PUBLISHED","assigner":"zephyr","published_at":"2026-10-19 23:17:36","updated_at":"2026-10-20 20:17:24"},"problem_types":["CWE-787","CWE-822","CWE-787 memory-safety","CWE-822 memory-safety"],"metrics":[{"version":"3.1","source":"vulnerabilities@zephyrproject.org","type":"Secondary","score":"6.1","severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H","baseScore":6.1,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"LOW","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"CVSS","score":"6.1","severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H","data":{"baseScore":6.1,"baseSeverity":"MEDIUM","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H","version":"3.1"}}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-7337-mc44-5wjm","name":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-7337-mc44-5wjm","refsource":"vulnerabilities@zephyrproject.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/bea93400138362691403b7f81de1e9048681547d","name":"https://github.com/zephyrproject-rtos/zephyr/commit/bea93400138362691403b7f81de1e9048681547d","refsource":"vulnerabilities@zephyrproject.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-19595","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-19595","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"zephyrproject","product":"zephyr","version":"affected 3.4.0 4.4.2 semver","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"19595","cve":"CVE-2026-19595","epss":"0.001120000","percentile":"0.012990000","score_date":"2026-10-20","updated_at":"2026-10-21 00:14:27"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"adp":[{"metrics":[{"other":{"content":{"id":"CVE-2026-19595","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","timestamp":"2026-10-20T19:21:33.416588Z","version":"2.0.3"},"type":"ssvc"}}],"providerMetadata":{"dateUpdated":"2026-10-20T19:21:46.367Z","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP"},"title":"CISA ADP Vulnrichment"}],"cna":{"affected":[{"collectionURL":"https://github.com/zephyrproject-rtos/zephyr","defaultStatus":"unaffected","packageName":"zephyr","product":"zephyr","programFiles":["subsys/rtio/rtio_handlers.c","subsys/rtio/rtio_syscalls.c"],"programRoutines":[{"name":"z_vrfy_rtio_cqe_get_mempool_buffer"}],"vendor":"zephyrproject","versions":[{"lessThanOrEqual":"4.4.2","status":"affected","version":"3.4.0","versionType":"semver"}]}],"descriptions":[{"lang":"en","value":"The user-mode syscall verifier z_vrfy_rtio_cqe_get_mempool_buffer() in subsys/rtio/rtio_syscalls.c validated its two output parameters, buff and buff_len, with K_SYSCALL_MEMORY_READ() rather than K_SYSCALL_MEMORY_WRITE(). Both are pure out-parameters: z_impl_rtio_cqe_get_mempool_buffer() stores the mempool buffer address and its length through them. The distinction is enforced by every architecture validator — arch_buffer_validate() on RISC-V PMP explicitly accepts the global __rom_region/__rodata_region for reads only, and the ARM MPU validators accept P_RO_U_RO and P_RW_U_RO regions for reads only — so a read-validated pointer is not necessarily writable by the calling thread.\n\nAn unprivileged user-mode thread that has been granted access to an RTIO context (rtio_access_grant()) can invoke the rtio_cqe_get_mempool_buffer() syscall with buff/buff_len pointing at memory it may read but not write, and with a completion-queue entry whose flags field it fully controls (only RTIO_CQE_FLAG_MEMPOOL_BUFFER in flags[7:0] is required; flags[19:8] and flags[31:20] supply the block index and count). The kernel then performs a pointer-sized and a 4-byte store through those addresses while running in supervisor mode. Reaching the store requires CONFIG_USERSPACE together with CONFIG_RTIO_SYS_MEM_BLOCKS, the configuration behind RTIO_DEFINE_WITH_MEMPOOL; without the latter the implementation returns -ENOTSUP and writes nothing.\n\nTwo outcomes follow. If the target lies in a memory-domain partition declared K_MEM_PARTITION_P_RW_U_RO (privileged read-write, user read-only), the kernel-mode store succeeds and deposits partly attacker-chosen values into memory the memory domain had marked read-only for that thread, bypassing the partition's write protection. If the target lies in globally readable but unwritable memory such as .text/.rodata in flash, the store faults in kernel mode; the fault is delivered to z_fatal_error() and the default k_sys_fatal_error_handler() halts or reboots the device, giving an unprivileged thread a reliable full denial of service.\n\nThe read-permission check does bound the damage: the address must still be readable by the calling thread, so kernel-private memory cannot be targeted and no confidential data is disclosed. The fix replaces both checks with K_SYSCALL_MEMORY_WRITE(), so a thread lacking write permission is terminated by K_OOPS before the implementation runs; the cqe argument correctly remains read-validated."}],"metrics":[{"cvssV3_1":{"baseScore":6.1,"baseSeverity":"MEDIUM","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H","version":"3.1"},"format":"CVSS"}],"problemTypes":[{"descriptions":[{"cweId":"CWE-787","description":"memory-safety","lang":"en","type":"CWE"},{"cweId":"CWE-822","description":"memory-safety","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-10-19T22:49:40.334Z","orgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","shortName":"zephyr"},"references":[{"name":"Fix commit","tags":["patch"],"url":"https://github.com/zephyrproject-rtos/zephyr/commit/bea93400138362691403b7f81de1e9048681547d"},{"name":"GHSA-7337-mc44-5wjm","url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-7337-mc44-5wjm"}],"title":"Zephyr RTIO syscall verifier validates output parameters for read instead of write access","x_generator":{"engine":"cvelib 1.8.0"}}},"cveMetadata":{"assignerOrgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","assignerShortName":"zephyr","cveId":"CVE-2026-19595","datePublished":"2026-10-19T22:49:40.334Z","dateReserved":"2026-08-12T05:34:36.022Z","dateUpdated":"2026-10-20T19:21:46.367Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-19 23:17:36","lastModifiedDate":"2026-10-20 20:17:24","problem_types":["CWE-787","CWE-822","CWE-787 memory-safety","CWE-822 memory-safety"],"metrics":{"cvssMetricV31":[{"source":"vulnerabilities@zephyrproject.org","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H","baseScore":6.1,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"LOW","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":4.2}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-10-20T19:21:33.416588Z","id":"CVE-2026-19595","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"19595","Ordinal":"1","Title":"Zephyr RTIO syscall verifier validates output parameters for rea","CVE":"CVE-2026-19595","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"19595","Ordinal":"1","NoteData":"The user-mode syscall verifier z_vrfy_rtio_cqe_get_mempool_buffer() in subsys/rtio/rtio_syscalls.c validated its two output parameters, buff and buff_len, with K_SYSCALL_MEMORY_READ() rather than K_SYSCALL_MEMORY_WRITE(). Both are pure out-parameters: z_impl_rtio_cqe_get_mempool_buffer() stores the mempool buffer address and its length through them. The distinction is enforced by every architecture validator — arch_buffer_validate() on RISC-V PMP explicitly accepts the global __rom_region/__rodata_region for reads only, and the ARM MPU validators accept P_RO_U_RO and P_RW_U_RO regions for reads only — so a read-validated pointer is not necessarily writable by the calling thread.\n\nAn unprivileged user-mode thread that has been granted access to an RTIO context (rtio_access_grant()) can invoke the rtio_cqe_get_mempool_buffer() syscall with buff/buff_len pointing at memory it may read but not write, and with a completion-queue entry whose flags field it fully controls (only RTIO_CQE_FLAG_MEMPOOL_BUFFER in flags[7:0] is required; flags[19:8] and flags[31:20] supply the block index and count). The kernel then performs a pointer-sized and a 4-byte store through those addresses while running in supervisor mode. Reaching the store requires CONFIG_USERSPACE together with CONFIG_RTIO_SYS_MEM_BLOCKS, the configuration behind RTIO_DEFINE_WITH_MEMPOOL; without the latter the implementation returns -ENOTSUP and writes nothing.\n\nTwo outcomes follow. If the target lies in a memory-domain partition declared K_MEM_PARTITION_P_RW_U_RO (privileged read-write, user read-only), the kernel-mode store succeeds and deposits partly attacker-chosen values into memory the memory domain had marked read-only for that thread, bypassing the partition's write protection. If the target lies in globally readable but unwritable memory such as .text/.rodata in flash, the store faults in kernel mode; the fault is delivered to z_fatal_error() and the default k_sys_fatal_error_handler() halts or reboots the device, giving an unprivileged thread a reliable full denial of service.\n\nThe read-permission check does bound the damage: the address must still be readable by the calling thread, so kernel-private memory cannot be targeted and no confidential data is disclosed. The fix replaces both checks with K_SYSCALL_MEMORY_WRITE(), so a thread lacking write permission is terminated by K_OOPS before the implementation runs; the cqe argument correctly remains read-validated.","Type":"Description","Title":"Zephyr RTIO syscall verifier validates output parameters for rea"}]}}}