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CVE-2026-81009 (GCVE-0-2026-81009)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:43 – Updated: 2026-09-11 19:43
VLAI
Title
io_uring/query: cap user size passed to copy_struct_to_user
Summary
In the Linux kernel, the following vulnerability has been resolved: io_uring/query: cap user size passed to copy_struct_to_user io_handle_query_entry() clamps hdr.size for the inbound copy_from_user() but keeps the original user value as usize. copy_struct_to_user() uses that usize and, when it is larger than the kernel result, clear_user()s the trailing bytes. As hdr.size is a __u32, a query can request nearly 4 GiB of zeroing, including on the error path where res_size stays 0. The interface is reachable without a ring via IORING_REGISTER_QUERY. Reject sizes larger than PAGE_SIZE, as recommended for copy_struct_* interfaces.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: c265ae75f900cea4e415230a77b5d152377627dd , < 417e02f7b6051765b91cf1289071882eebd172e0 (git)
Affected: c265ae75f900cea4e415230a77b5d152377627dd , < 2b8ad4981ecedb14c1fdd811ab977010b23933e6 (git)
Affected: c265ae75f900cea4e415230a77b5d152377627dd , < ba77efee1b95b4ad7559b1cdbe7cd7fa36dca95b (git)
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Linux Linux Affected: 6.18
Unaffected: 0 , < 6.18 (semver)
Unaffected: 6.18.50 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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          "product": "Linux",
          "programFiles": [
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              "operator": "OR"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/query: cap user size passed to copy_struct_to_user\n\nio_handle_query_entry() clamps hdr.size for the inbound copy_from_user()\nbut keeps the original user value as usize. copy_struct_to_user() uses\nthat usize and, when it is larger than the kernel result, clear_user()s\nthe trailing bytes.\n\nAs hdr.size is a __u32, a query can request nearly 4 GiB of zeroing,\nincluding on the error path where res_size stays 0. The interface is\nreachable without a ring via IORING_REGISTER_QUERY.\n\nReject sizes larger than PAGE_SIZE, as recommended for copy_struct_*\ninterfaces."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-11T19:43:00.074Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        },
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          "url": "https://git.kernel.org/stable/c/ba77efee1b95b4ad7559b1cdbe7cd7fa36dca95b"
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    "datePublished": "2026-09-11T19:43:00.074Z",
    "dateReserved": "2026-08-26T14:34:25.812Z",
    "dateUpdated": "2026-09-11T19:43:00.074Z",
    "state": "PUBLISHED"
  },
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      "percentile": "0.06261"
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        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/query: cap user size passed to copy_struct_to_user\n\nio_handle_query_entry() clamps hdr.size for the inbound copy_from_user()\nbut keeps the original user value as usize. copy_struct_to_user() uses\nthat usize and, when it is larger than the kernel result, clear_user()s\nthe trailing bytes.\n\nAs hdr.size is a __u32, a query can request nearly 4 GiB of zeroing,\nincluding on the error path where res_size stays 0. The interface is\nreachable without a ring via IORING_REGISTER_QUERY.\n\nReject sizes larger than PAGE_SIZE, as recommended for copy_struct_*\ninterfaces."
          }
        ],
        "id": "CVE-2026-81009",
        "lastModified": "2026-09-11T20:19:09.687",
        "metrics": {},
        "published": "2026-09-11T20:19:09.687",
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      "cve": "CVE-2026-81009",
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      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: io_uring/query: cap user size passed to copy_struct_to_user",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-81009.json",
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      "cve": "CVE-2026-81009",
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      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-81009.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • 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.


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