CVE-2026-52944 (GCVE-0-2026-52944)
Vulnerability from cvelistv5
Published
2026-06-24 09:59
Modified
2026-09-14 11:58
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix FSCTL permission bypass by adding a permission check for FSCTL_SET_SPARSE FSCTL_SET_SPARSE in fsctl_set_sparse() modifies the file's sparse attribute and saves it through xattr without any permission checks. This exposes two issues: 1) A client on a read-only share can change the sparse attribute on files it opened, even though the share is read-only. Other FSCTL write operations already check test_tree_conn_flag(work->tcon, KSMBD_TREE_CONN_FLAG_WRITABLE), but FSCTL_SET_SPARSE does not. 2) Even on writable shares, clients without FILE_WRITE_DATA or FILE_WRITE_ATTRIBUTES access should not modify the sparse attribute. Similar handle-level checks exist in other functions but are missing here. Add both share-level writable check and per-handle access check. Use goto out on error to avoid leaking file references.
References
Impacted products
Vendor Product Version
Linux Linux Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
Version: e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9
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{
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smb2pdu.c"
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      "cpeApplicability": [
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix FSCTL permission bypass by adding a permission check for FSCTL_SET_SPARSE\n\nFSCTL_SET_SPARSE in fsctl_set_sparse() modifies the file\u0027s sparse\nattribute and saves it through xattr without any permission checks.\n\nThis exposes two issues:\n\n1) A client on a read-only share can change the sparse attribute\n   on files it opened, even though the share is read-only.\n   Other FSCTL write operations already check\n   test_tree_conn_flag(work-\u003etcon, KSMBD_TREE_CONN_FLAG_WRITABLE),\n   but FSCTL_SET_SPARSE does not.\n\n2) Even on writable shares, clients without FILE_WRITE_DATA or\n   FILE_WRITE_ATTRIBUTES access should not modify the sparse\n   attribute. Similar handle-level checks exist in other functions\n   but are missing here.\n\nAdd both share-level writable check and per-handle access check.\nUse goto out on error to avoid leaking file references."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-14T11:58:26.890Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/ef664475c1bf1a27d45dae6848ca9c9c4d86853f"
        },
        {
          "url": "https://git.kernel.org/stable/c/3a9a0a1c38ef90788f5d7c4b29903c8b220f744a"
        },
        {
          "url": "https://git.kernel.org/stable/c/3127a884525dc8ca4def73254bfcd3ccef0bf812"
        },
        {
          "url": "https://git.kernel.org/stable/c/c5ab11263e3c89aa7989afc5374ef7743e092fd0"
        },
        {
          "url": "https://git.kernel.org/stable/c/de9eb0b44fa9123170e6245b49638e0e453c10f8"
        },
        {
          "url": "https://git.kernel.org/stable/c/aef151bcfa494bfe983669de2726734b534adb73"
        },
        {
          "url": "https://git.kernel.org/stable/c/cc57232cae23c0df91b4a59d0f519141ce9b5b02"
        }
      ],
      "title": "ksmbd: fix FSCTL permission bypass by adding a permission check for FSCTL_SET_SPARSE",
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-52944",
    "datePublished": "2026-06-24T09:59:09.149Z",
    "dateReserved": "2026-06-09T07:44:35.371Z",
    "dateUpdated": "2026-09-14T11:58:26.890Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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