CVE-2026-16511 (GCVE-0-2026-16511)

Vulnerability from cvelistv5 – Published: 2026-11-04 06:09 – Updated: 2026-11-04 06:09
VLAI
Title
Unvalidated user pointers in RTIO syscall verifiers allow a user-mode thread to write kernel memory
Summary
Two RTIO syscall verifiers, in subsys/rtio/rtio_syscalls.c (subsys/rtio/rtio_handlers.c before v4.3.0), did not validate user-supplied pointers before the kernel wrote through them. z_vrfy_rtio_sqe_cancel() performed no validation at all. It passed the caller's struct rtio_sqe pointer straight to z_impl_rtio_sqe_cancel(), which converts it with CONTAINER_OF to a struct rtio_iodev_sqe, ORs RTIO_SQE_CANCELED (BIT(3)) into its 16-bit flags field in supervisor mode, then loads its next pointer and repeats until that pointer is NULL. The syscall takes no RTIO context argument, so it needs no object grant: any user-mode thread on a CONFIG_USERSPACE build can set that bit in a 16-bit word at an address of its choosing in kernel memory, and the kernel continues the write along whatever pointer chain it finds at the corresponding offset. Setting chosen bits in kernel data structures, such as object permission or thread state fields, can be used to escalate privilege from user mode. z_vrfy_rtio_sqe_copy_in_get_handles() validated its RTIO context and the input SQE array, but only NULL-checked the handle out-parameter before writing a kernel SQE pointer through it, with no K_SYSCALL_MEMORY_WRITE check. A user thread that holds a granted RTIO context can therefore make the kernel store a pointer value at an arbitrary address. The fixes validate the handle out-parameter as writable, bound the cancel handle to real submission-pool storage, and require permission on the RTIO context that owns the matching pool. Without that last check a bounded handle still let any user thread cancel submissions belonging to other contexts, silently aborting their I/O. Systems built without CONFIG_USERSPACE or without CONFIG_RTIO are unaffected.
Severity
8.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CWE
Assigner
zephyr CNA under the mitre root
CNA scorecard B 77/100 over 213 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
zephyrproject zephyr Affected: 3.4.0 , < 4.3.2 (semver)
Affected: 4.4.0 , < 4.5.0 (semver)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "collectionURL": "https://github.com/zephyrproject-rtos/zephyr",
          "defaultStatus": "unaffected",
          "packageName": "zephyr",
          "product": "zephyr",
          "programFiles": [
            "include/zephyr/rtio/rtio.h",
            "subsys/rtio/rtio_handlers.c",
            "subsys/rtio/rtio_syscalls.c"
          ],
          "programRoutines": [
            {
              "name": "z_impl_rtio_sqe_cancel"
            },
            {
              "name": "z_vrfy_rtio_sqe_cancel"
            },
            {
              "name": "z_vrfy_rtio_sqe_copy_in_get_handles"
            }
          ],
          "vendor": "zephyrproject",
          "versions": [
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              "lessThan": "4.3.2",
              "status": "affected",
              "version": "3.4.0",
              "versionType": "semver"
            },
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          "value": "Two RTIO syscall verifiers, in subsys/rtio/rtio_syscalls.c (subsys/rtio/rtio_handlers.c before v4.3.0), did not validate user-supplied pointers before the kernel wrote through them.\n\nz_vrfy_rtio_sqe_cancel() performed no validation at all. It passed the caller\u0027s struct rtio_sqe pointer straight to z_impl_rtio_sqe_cancel(), which converts it with CONTAINER_OF to a struct rtio_iodev_sqe, ORs RTIO_SQE_CANCELED (BIT(3)) into its 16-bit flags field in supervisor mode, then loads its next pointer and repeats until that pointer is NULL. The syscall takes no RTIO context argument, so it needs no object grant: any user-mode thread on a CONFIG_USERSPACE build can set that bit in a 16-bit word at an address of its choosing in kernel memory, and the kernel continues the write along whatever pointer chain it finds at the corresponding offset. Setting chosen bits in kernel data structures, such as object permission or thread state fields, can be used to escalate privilege from user mode.\n\nz_vrfy_rtio_sqe_copy_in_get_handles() validated its RTIO context and the input SQE array, but only NULL-checked the handle out-parameter before writing a kernel SQE pointer through it, with no K_SYSCALL_MEMORY_WRITE check. A user thread that holds a granted RTIO context can therefore make the kernel store a pointer value at an arbitrary address.\n\nThe fixes validate the handle out-parameter as writable, bound the cancel handle to real submission-pool storage, and require permission on the RTIO context that owns the matching pool. Without that last check a bounded handle still let any user thread cancel submissions belonging to other contexts, silently aborting their I/O. Systems built without CONFIG_USERSPACE or without CONFIG_RTIO are unaffected."
        }
      ],
      "metrics": [
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
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            {
              "cweId": "CWE-787",
              "description": "memory-safety",
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            },
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              "description": "memory-safety",
              "lang": "en",
              "type": "CWE"
            }
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      ],
      "providerMetadata": {
        "dateUpdated": "2026-11-04T06:09:02.527Z",
        "orgId": "e2e69745-5e70-4e92-8431-deb5529a81ad",
        "shortName": "zephyr"
      },
      "references": [
        {
          "name": "Fix commit b1092a0aa7fb",
          "tags": [
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          ],
          "url": "https://github.com/zephyrproject-rtos/zephyr/commit/b1092a0aa7fbe67118ca4b08d5b4e54b34709a6e"
        },
        {
          "name": "Fix commit 95c355c42576",
          "tags": [
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          "url": "https://github.com/zephyrproject-rtos/zephyr/commit/95c355c425763fbe5e735b9ef54dacce2c4ce21f"
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          "tags": [
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          "url": "https://github.com/zephyrproject-rtos/zephyr/commit/3f244c1709ec0be533ed83d34998e942fc4da399"
        },
        {
          "name": "GHSA-3rh4-hpgj-jrww",
          "url": "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-3rh4-hpgj-jrww"
        }
      ],
      "title": "Unvalidated user pointers in RTIO syscall verifiers allow a user-mode thread to write kernel memory",
      "x_generator": {
        "engine": "cvelib 1.8.0"
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  "cveMetadata": {
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    "assignerShortName": "zephyr",
    "cveId": "CVE-2026-16511",
    "datePublished": "2026-11-04T06:09:02.527Z",
    "dateReserved": "2026-07-21T21:42:56.147Z",
    "dateUpdated": "2026-11-04T06:09:02.527Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "date": "2026-11-08",
      "epss": "0.00173",
      "percentile": "0.06815"
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                "collectionURL": "https://github.com/zephyrproject-rtos/zephyr",
                "defaultStatus": "unaffected",
                "packageName": "zephyr",
                "product": "zephyr",
                "programFiles": [
                  "include/zephyr/rtio/rtio.h",
                  "subsys/rtio/rtio_handlers.c",
                  "subsys/rtio/rtio_syscalls.c"
                ],
                "programRoutines": [
                  {
                    "name": "z_impl_rtio_sqe_cancel"
                  },
                  {
                    "name": "z_vrfy_rtio_sqe_cancel"
                  },
                  {
                    "name": "z_vrfy_rtio_sqe_copy_in_get_handles"
                  }
                ],
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        "descriptions": [
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            "value": "Two RTIO syscall verifiers, in subsys/rtio/rtio_syscalls.c (subsys/rtio/rtio_handlers.c before v4.3.0), did not validate user-supplied pointers before the kernel wrote through them.\n\nz_vrfy_rtio_sqe_cancel() performed no validation at all. It passed the caller\u0027s struct rtio_sqe pointer straight to z_impl_rtio_sqe_cancel(), which converts it with CONTAINER_OF to a struct rtio_iodev_sqe, ORs RTIO_SQE_CANCELED (BIT(3)) into its 16-bit flags field in supervisor mode, then loads its next pointer and repeats until that pointer is NULL. The syscall takes no RTIO context argument, so it needs no object grant: any user-mode thread on a CONFIG_USERSPACE build can set that bit in a 16-bit word at an address of its choosing in kernel memory, and the kernel continues the write along whatever pointer chain it finds at the corresponding offset. Setting chosen bits in kernel data structures, such as object permission or thread state fields, can be used to escalate privilege from user mode.\n\nz_vrfy_rtio_sqe_copy_in_get_handles() validated its RTIO context and the input SQE array, but only NULL-checked the handle out-parameter before writing a kernel SQE pointer through it, with no K_SYSCALL_MEMORY_WRITE check. A user thread that holds a granted RTIO context can therefore make the kernel store a pointer value at an arbitrary address.\n\nThe fixes validate the handle out-parameter as writable, bound the cancel handle to real submission-pool storage, and require permission on the RTIO context that owns the matching pool. Without that last check a bounded handle still let any user thread cancel submissions belonging to other contexts, silently aborting their I/O. Systems built without CONFIG_USERSPACE or without CONFIG_RTIO are unaffected."
          }
        ],
        "id": "CVE-2026-16511",
        "lastModified": "2026-11-04T06:17:04.263",
        "metrics": {
          "cvssMetricV31": [
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                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "CHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
                "version": "3.1"
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            "source": "vulnerabilities@zephyrproject.org",
            "url": "https://github.com/zephyrproject-rtos/zephyr/commit/b1092a0aa7fbe67118ca4b08d5b4e54b34709a6e"
          },
          {
            "source": "vulnerabilities@zephyrproject.org",
            "url": "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-3rh4-hpgj-jrww"
          }
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        "sourceIdentifier": "vulnerabilities@zephyrproject.org",
        "vulnStatus": "Awaiting Analysis",
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                "value": "CWE-787"
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            "source": "vulnerabilities@zephyrproject.org",
            "type": "Secondary"
          }
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}



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