GHSA-MRP6-592V-C3FH

Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-27 06:30
VLAI
Details

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

ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE

The FSCTL_DUPLICATE_EXTENTS_TO_FILE arm of smb2_ioctl() overwrites the destination file's data via vfs_clone_file_range() with neither the share-level KSMBD_TREE_CONN_FLAG_WRITABLE check nor a per-handle fp->daccess check that the other write-bearing arms carry. A client can overwrite destination data on a read-only share, or from a handle opened with only FILE_WRITE_ATTRIBUTES (which still yields an FMODE_WRITE filp). FILE_WRITE_ATTRIBUTES-only destination handle overwrote the file's data via the clone. Add both checks, matching the FSCTL_SET_SPARSE permission fix; require FILE_WRITE_DATA since this writes data.

Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-64399"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-25T10:17:23Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE\n\nThe FSCTL_DUPLICATE_EXTENTS_TO_FILE arm of smb2_ioctl() overwrites the\ndestination file\u0027s data via vfs_clone_file_range() with neither the\nshare-level KSMBD_TREE_CONN_FLAG_WRITABLE check nor a per-handle\nfp-\u003edaccess check that the other write-bearing arms carry. A client can\noverwrite destination data on a read-only share, or from a handle opened\nwith only FILE_WRITE_ATTRIBUTES (which still yields an FMODE_WRITE filp).\nFILE_WRITE_ATTRIBUTES-only destination handle overwrote the file\u0027s data via\nthe clone. Add both checks, matching the FSCTL_SET_SPARSE permission fix;\nrequire FILE_WRITE_DATA since this writes data.",
  "id": "GHSA-mrp6-592v-c3fh",
  "modified": "2026-07-27T06:30:36Z",
  "published": "2026-07-25T12:31:34Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64399"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/388e4139db27a9e3612c9d356b826f5b1ff6a9e3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/620d133d469295ee7c017ca6aafac335f65c4a5a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9b9cf7e65cbeaae1b6636144bacee611cdd7a5d6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/baae7b39673ec21073a25e3d14f8feaada01d5df"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bf460ad5958d506492de4524a656439da3f99c51"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c917e4522d251071dde9871b9142d8ea1186ebfe"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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