CVE-2026-64395 (GCVE-0-2026-64395)
Vulnerability from cvelistv5
Published
2026-07-25 08:50
Modified
2026-08-17 04:54
Severity ?
7.5 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: require source read access for duplicate extents FSCTL_DUPLICATE_EXTENTS_TO_FILE passes the source file directly to vfs_clone_file_range() or vfs_copy_file_range() without checking the SMB access mask granted to the source handle. A handle opened with attribute access can consequently be used to copy file contents into an attacker-readable destination. Require FILE_READ_DATA on the source handle before either VFS operation, matching other ksmbd data-copy paths.
References
Impacted products
Vendor Product Version
Linux Linux Version: eb817368f50c1cbe1bd07044124aad7db6330e3a
Version: eb817368f50c1cbe1bd07044124aad7db6330e3a
Version: eb817368f50c1cbe1bd07044124aad7db6330e3a
Version: eb817368f50c1cbe1bd07044124aad7db6330e3a
Version: eb817368f50c1cbe1bd07044124aad7db6330e3a
Version: eb817368f50c1cbe1bd07044124aad7db6330e3a
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/server/smb2pdu.c"
          ],
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          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
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              "version": "5.15"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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            {
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              "status": "unaffected",
              "version": "6.1.178",
              "versionType": "semver"
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            {
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              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.96",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.39",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.178",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.145",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: require source read access for duplicate extents\n\nFSCTL_DUPLICATE_EXTENTS_TO_FILE passes the source file directly to\nvfs_clone_file_range() or vfs_copy_file_range() without checking the SMB\naccess mask granted to the source handle. A handle opened with attribute\naccess can consequently be used to copy file contents into an\nattacker-readable destination.\n\nRequire FILE_READ_DATA on the source handle before either VFS operation,\nmatching other ksmbd data-copy paths."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The vulnerable SMB2 IOCTL is remotely reachable through ksmbd over TCP, normally port 445.\nAC:L - The attacker controls both handles, offsets, and copy length; no race is required, and exploitation is reliable on common reflink-capable filesystems such as XFS and Btrfs.\nPR:N - In a reasonable guest-enabled writable-share deployment, an unauthenticated remote attacker can establish a guest session without credentials and obtain the required attribute-only source and writable destination handles.\nUI:N - After connecting to the share, the attacker can open both handles and issue the IOCTL without any victim action.\nS:U - The bypass discloses files governed by the same kernel and SMB server security authority and does not cross a virtualization or other security scope.\nC:H - Attacker-controlled offsets and lengths allow complete copying of otherwise unreadable files into an attacker-readable destination, causing total confidentiality loss for protected share contents.\nI:N - The source is not modified, and the destination must already be on a writable tree and opened with FILE_WRITE_DATA, so the flaw adds no unauthorized modification capability.\nA:N - The operation does not corrupt memory, crash the kernel, or inherently disrupt service; any destination writes are already authorized by the required handle permissions."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:54:49.007Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/2d2ab6983620c2d60ce7db72133984ca3873b929"
        },
        {
          "url": "https://git.kernel.org/stable/c/67bdad9cf01b25030e3bf00bbce6c309319d6663"
        },
        {
          "url": "https://git.kernel.org/stable/c/b0d4d5cb846a1ddb7aaab9adfb5986e4540e6e5f"
        },
        {
          "url": "https://git.kernel.org/stable/c/db231af842868268839f9f9619c68cb27830d8be"
        },
        {
          "url": "https://git.kernel.org/stable/c/a10942af27832c2761d020863a46e79bebe0567d"
        },
        {
          "url": "https://git.kernel.org/stable/c/cedff600f1642aa982178503552f0d007bc829c8"
        }
      ],
      "title": "ksmbd: require source read access for duplicate extents",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64395",
    "datePublished": "2026-07-25T08:50:40.393Z",
    "dateReserved": "2026-07-19T15:36:31.785Z",
    "dateUpdated": "2026-08-17T04:54:49.007Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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