CVE-2026-31432 (GCVE-0-2026-31432)
Vulnerability from cvelistv5
Published
2026-04-22 08:15
Modified
2026-04-27 14:03
Severity ?
8.8 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix OOB write in QUERY_INFO for compound requests When a compound request such as READ + QUERY_INFO(Security) is received, and the first command (READ) consumes most of the response buffer, ksmbd could write beyond the allocated buffer while building a security descriptor. The root cause was that smb2_get_info_sec() checked buffer space using ppntsd_size from xattr, while build_sec_desc() often synthesized a significantly larger descriptor from POSIX ACLs. This patch introduces smb_acl_sec_desc_scratch_len() to accurately compute the final descriptor size beforehand, performs proper buffer checking with smb2_calc_max_out_buf_len(), and uses exact-sized allocation + iov pinning.
References
Impacted products
Vendor Product Version
Linux Linux Version: e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d
Version: e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d
Version: e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d
Version: e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d
Version: f2283680a80571ca82d710bc6ecd8f8beac67d63
Version: 9f297df20d93411c0b4ddad7f88ba04a7cd36e77
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{
  "containers": {
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        {
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          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smb2pdu.c",
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          ],
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              "version": "6.19.12",
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              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix OOB write in QUERY_INFO for compound requests\n\nWhen a compound request such as READ + QUERY_INFO(Security) is received,\nand the first command (READ) consumes most of the response buffer,\nksmbd could write beyond the allocated buffer while building a security\ndescriptor.\n\nThe root cause was that smb2_get_info_sec() checked buffer space using\nppntsd_size from xattr, while build_sec_desc() often synthesized a\nsignificantly larger descriptor from POSIX ACLs.\n\nThis patch introduces smb_acl_sec_desc_scratch_len() to accurately\ncompute the final descriptor size beforehand, performs proper buffer\nchecking with smb2_calc_max_out_buf_len(), and uses exact-sized\nallocation + iov pinning."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-27T14:03:04.638Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/d48c64fb80ad78b3dd29fb7d79b6ec7bd72bfc09"
        },
        {
          "url": "https://git.kernel.org/stable/c/075ea208c648cc2bcd616295b711d3637c61de45"
        },
        {
          "url": "https://git.kernel.org/stable/c/515c2daab46021221bdf406bef19bc90a44ec617"
        },
        {
          "url": "https://git.kernel.org/stable/c/fda9522ed6afaec45cabc198d8492270c394c7bc"
        }
      ],
      "title": "ksmbd: fix OOB write in QUERY_INFO for compound requests",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-31432",
    "datePublished": "2026-04-22T08:15:10.873Z",
    "dateReserved": "2026-03-09T15:48:24.089Z",
    "dateUpdated": "2026-04-27T14:03:04.638Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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