CVE-2026-31708 (GCVE-0-2026-31708)
Vulnerability from cvelistv5
Published
2026-05-01 13:56
Modified
2026-05-03 05:45
Severity ?
8.1 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path smb2_ioctl_query_info() has two response-copy branches: PASSTHRU_FSCTL and the default QUERY_INFO path. The QUERY_INFO branch clamps qi.input_buffer_length to the server-reported OutputBufferLength and then copies qi.input_buffer_length bytes from qi_rsp->Buffer to userspace, but it never verifies that the flexible-array payload actually fits within rsp_iov[1].iov_len. A malicious server can return OutputBufferLength larger than the actual QUERY_INFO response, causing copy_to_user() to walk past the response buffer and expose adjacent kernel heap to userspace. Guard the QUERY_INFO copy with a bounds check on the actual Buffer payload. Use struct_size(qi_rsp, Buffer, qi.input_buffer_length) rather than an open-coded addition so the guard cannot overflow on 32-bit builds.
References
Impacted products
Vendor Product Version
Linux Linux Version: f5778c398713692a16150ae96e5c8270bab8399f
Version: f5778c398713692a16150ae96e5c8270bab8399f
Version: f5778c398713692a16150ae96e5c8270bab8399f
Version: f5778c398713692a16150ae96e5c8270bab8399f
Version: f5778c398713692a16150ae96e5c8270bab8399f
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          "programFiles": [
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      "cpeApplicability": [
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          "nodes": [
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path\n\nsmb2_ioctl_query_info() has two response-copy branches: PASSTHRU_FSCTL\nand the default QUERY_INFO path.  The QUERY_INFO branch clamps\nqi.input_buffer_length to the server-reported OutputBufferLength and then\ncopies qi.input_buffer_length bytes from qi_rsp-\u003eBuffer to userspace, but\nit never verifies that the flexible-array payload actually fits within\nrsp_iov[1].iov_len.\n\nA malicious server can return OutputBufferLength larger than the actual\nQUERY_INFO response, causing copy_to_user() to walk past the response\nbuffer and expose adjacent kernel heap to userspace.\n\nGuard the QUERY_INFO copy with a bounds check on the actual Buffer\npayload.  Use struct_size(qi_rsp, Buffer, qi.input_buffer_length)\nrather than an open-coded addition so the guard cannot overflow on\n32-bit builds."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H",
            "version": "3.1"
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      "providerMetadata": {
        "dateUpdated": "2026-05-03T05:45:31.965Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a34d456934fe42e4da5d2cc07787bf418bee99c6"
        },
        {
          "url": "https://git.kernel.org/stable/c/ac2f14e4705d020f04e806efa0d49ab8dc2b145f"
        },
        {
          "url": "https://git.kernel.org/stable/c/078fae8f50adebb903ccf2252b44391324571e78"
        },
        {
          "url": "https://git.kernel.org/stable/c/85fd46ee26a11841c670449508025965f61ce131"
        },
        {
          "url": "https://git.kernel.org/stable/c/a58c5af19ff0d6f44f6e9fe31e33a2c92223f77e"
        }
      ],
      "title": "smb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-31708",
    "datePublished": "2026-05-01T13:56:05.880Z",
    "dateReserved": "2026-03-09T15:48:24.132Z",
    "dateUpdated": "2026-05-03T05:45:31.965Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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