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GHSA-CMW3-52P3-WRX5

Vulnerability from github – Published: 2026-05-08 15:31 – Updated: 2026-05-11 09:30

Details

In the Linux kernel, the following vulnerability has been resolved:

io_uring: fix physical SQE bounds check for SQE_MIXED 128-byte ops

When IORING_SETUP_SQE_MIXED is used without IORING_SETUP_NO_SQARRAY, the boundary check for 128-byte SQE operations in io_init_req() validated the logical SQ head position rather than the physical SQE index.

The existing check:

!(ctx->cached_sq_head & (ctx->sq_entries - 1))

ensures the logical position isn't at the end of the ring, which is correct for NO_SQARRAY rings where physical == logical. However, when sq_array is present, an unprivileged user can remap any logical position to an arbitrary physical index via sq_array. Setting sq_array[N] = sq_entries - 1 places a 128-byte operation at the last physical SQE slot, causing the 128-byte memcpy in io_uring_cmd_sqe_copy() to read 64 bytes past the end of the SQE array.

Replace the cached_sq_head alignment check with a direct validation of the physical SQE index, which correctly handles both sq_array and NO_SQARRAY cases.

Severity

7.1 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-43442"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-08T15:16:56Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring: fix physical SQE bounds check for SQE_MIXED 128-byte ops\n\nWhen IORING_SETUP_SQE_MIXED is used without IORING_SETUP_NO_SQARRAY,\nthe boundary check for 128-byte SQE operations in io_init_req()\nvalidated the logical SQ head position rather than the physical SQE\nindex.\n\nThe existing check:\n\n  !(ctx-\u003ecached_sq_head \u0026 (ctx-\u003esq_entries - 1))\n\nensures the logical position isn\u0027t at the end of the ring, which is\ncorrect for NO_SQARRAY rings where physical == logical. However, when\nsq_array is present, an unprivileged user can remap any logical\nposition to an arbitrary physical index via sq_array. Setting\nsq_array[N] = sq_entries - 1 places a 128-byte operation at the last\nphysical SQE slot, causing the 128-byte memcpy in\nio_uring_cmd_sqe_copy() to read 64 bytes past the end of the SQE\narray.\n\nReplace the cached_sq_head alignment check with a direct validation\nof the physical SQE index, which correctly handles both sq_array and\nNO_SQARRAY cases.",
  "id": "GHSA-cmw3-52p3-wrx5",
  "modified": "2026-05-11T09:30:31Z",
  "published": "2026-05-08T15:31:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43442"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1f794f9bed3e5cf7250a3b4daf112a72ed1513e9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6f02c6b196036dbb6defb4647d8707d29b7fe95b"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-43442 (GCVE-0-2026-43442)

Vulnerability from cvelistv5 – Published: 2026-05-08 14:22 – Updated: 2026-08-05 12:27

Title

io_uring: fix physical SQE bounds check for SQE_MIXED 128-byte ops

Summary

In the Linux kernel, the following vulnerability has been resolved: io_uring: fix physical SQE bounds check for SQE_MIXED 128-byte ops When IORING_SETUP_SQE_MIXED is used without IORING_SETUP_NO_SQARRAY, the boundary check for 128-byte SQE operations in io_init_req() validated the logical SQ head position rather than the physical SQE index. The existing check: !(ctx->cached_sq_head & (ctx->sq_entries - 1)) ensures the logical position isn't at the end of the ring, which is correct for NO_SQARRAY rings where physical == logical. However, when sq_array is present, an unprivileged user can remap any logical position to an arbitrary physical index via sq_array. Setting sq_array[N] = sq_entries - 1 places a 128-byte operation at the last physical SQE slot, causing the 128-byte memcpy in io_uring_cmd_sqe_copy() to read 64 bytes past the end of the SQE array. Replace the cached_sq_head alignment check with a direct validation of the physical SQE index, which correctly handles both sq_array and NO_SQARRAY cases.

Severity

7.1 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Assigner

Linux mitre root Scorecard

References

2 references

URL	Tags
https://git.kernel.org/stable/c/1f794f9bed3e5cf72…
https://git.kernel.org/stable/c/6f02c6b196036dbb6…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 1cba30bf9fdd6c982708f3587f609a30c370d889 , < 1f794f9bed3e5cf7250a3b4daf112a72ed1513e9 (git) Affected: 1cba30bf9fdd6c982708f3587f609a30c370d889 , < 6f02c6b196036dbb6defb4647d8707d29b7fe95b (git)
Linux	Linux	Affected: 6.19 Unaffected: 0 , < 6.19 (semver) Unaffected: 6.19.9 , ≤ 6.19.* (semver) Unaffected: 7.0 , ≤ * (original_commit_for_fix)

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JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "io_uring/io_uring.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "1f794f9bed3e5cf7250a3b4daf112a72ed1513e9",
              "status": "affected",
              "version": "1cba30bf9fdd6c982708f3587f609a30c370d889",
              "versionType": "git"
            },
            {
              "lessThan": "6f02c6b196036dbb6defb4647d8707d29b7fe95b",
              "status": "affected",
              "version": "1cba30bf9fdd6c982708f3587f609a30c370d889",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "io_uring/io_uring.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.19"
            },
            {
              "lessThan": "6.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.9",
                  "versionStartIncluding": "6.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "6.19",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring: fix physical SQE bounds check for SQE_MIXED 128-byte ops\n\nWhen IORING_SETUP_SQE_MIXED is used without IORING_SETUP_NO_SQARRAY,\nthe boundary check for 128-byte SQE operations in io_init_req()\nvalidated the logical SQ head position rather than the physical SQE\nindex.\n\nThe existing check:\n\n  !(ctx-\u003ecached_sq_head \u0026 (ctx-\u003esq_entries - 1))\n\nensures the logical position isn\u0027t at the end of the ring, which is\ncorrect for NO_SQARRAY rings where physical == logical. However, when\nsq_array is present, an unprivileged user can remap any logical\nposition to an arbitrary physical index via sq_array. Setting\nsq_array[N] = sq_entries - 1 places a 128-byte operation at the last\nphysical SQE slot, causing the 128-byte memcpy in\nio_uring_cmd_sqe_copy() to read 64 bytes past the end of the SQE\narray.\n\nReplace the cached_sq_head alignment check with a direct validation\nof the physical SQE index, which correctly handles both sq_array and\nNO_SQARRAY cases."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerable path is reached through local io_uring syscalls and userspace-controlled SQ/SQE mappings, not by remote packets or physical access.\nAC:L - The attacker controls ring setup flags, sq_array contents, SQEs, and submission order; no race or external timing condition is required.\nPR:L - A basic unprivileged local user can create io_uring instances on the default kernel.io_uring_disabled=0 configuration and can use accessible uring_cmd files such as /dev/null or sockets.\nUI:N - Exploitation only requires the attacker\u0027s own syscall sequence and mapped ring manipulation, with no victim action.\nS:U - The issue remains within the kernel security authority and does not cross a VM, IOMMU, or other separate security boundary.\nC:H - The bad 128-byte memcpy can read 64 bytes past the SQE array; for page-boundary layouts this can read adjacent kernel memory, so confidentiality impact is high.\nI:N - The investigated primitive is an out-of-bounds read into a valid request buffer, with no out-of-bounds write or direct arbitrary modification primitive identified.\nA:H - The same out-of-bounds read can fault or trigger kernel diagnostics/oops conditions and is repeatable by the local attacker."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:27:59.003Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/1f794f9bed3e5cf7250a3b4daf112a72ed1513e9"
        },
        {
          "url": "https://git.kernel.org/stable/c/6f02c6b196036dbb6defb4647d8707d29b7fe95b"
        }
      ],
      "title": "io_uring: fix physical SQE bounds check for SQE_MIXED 128-byte ops",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43442",
    "datePublished": "2026-05-08T14:22:10.656Z",
    "dateReserved": "2026-05-01T14:12:56.009Z",
    "dateUpdated": "2026-08-05T12:27:59.003Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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GHSA-CMW3-52P3-WRX5

CVE-2026-43442 (GCVE-0-2026-43442)

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