{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9"
            },
            {
              "fixed": "25377f369688dd0bd814dc8965ed26d44238ecaa"
            },
            {
              "fixed": "3072d82461f498c85daea8766e9d8bfbada31605"
            },
            {
              "fixed": "ca53bb17f4e8232cfaece3953d3cef62c559b039"
            },
            {
              "fixed": "57f2042fd87d7ce8fc3ac8b6c176e554df68b1a7"
            },
            {
              "fixed": "deffa929086d7902e30918adf3dd27ccfe9c08b1"
            },
            {
              "fixed": "3320ba068198adc144c89d6661b805acce01735b"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.15.0"
            },
            {
              "fixed": "6.1.178"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.145"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.96"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.39"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.1.4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64398.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: add a permission check for FSCTL_SET_ZERO_DATA\n\nFSCTL_SET_ZERO_DATA in smb2_ioctl() destroys file data via\nksmbd_vfs_zero_data() -\u003e vfs_fallocate(PUNCH_HOLE/ZERO_RANGE) after\nchecking only the share-level KSMBD_TREE_CONN_FLAG_WRITABLE, with no\nper-handle access check. A handle opened with only FILE_WRITE_ATTRIBUTES\nstill yields an FMODE_WRITE filp (FILE_WRITE_ATTRIBUTES is part of\nFILE_WRITE_DESIRE_ACCESS_LE, so smb2_create_open_flags() opens it\nO_WRONLY), so the vfs_fallocate FMODE_WRITE check does not stop it; only\nthe missing fp-\u003edaccess gate would. Reproduced on mainline 7.1-rc7 with\nKASAN by an authenticated SMB client: a FILE_WRITE_ATTRIBUTES-only handle\nzeroed 4096 bytes of file data it had no FILE_WRITE_DATA right to\n(6/6; a FILE_READ_DATA-only handle was correctly denied).\n\nThis is the unfixed sibling of commit cc57232cae23 (\"ksmbd: fix FSCTL\npermission bypass by adding a permission check for FSCTL_SET_SPARSE\").\nBecause SET_ZERO_DATA writes data (not an attribute), require\nFILE_WRITE_DATA.",
  "id": "CVE-2026-64398",
  "modified": "2026-07-28T03:55:42.099297218Z",
  "published": "2026-07-25T08:50:42.221Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/25377f369688dd0bd814dc8965ed26d44238ecaa"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3072d82461f498c85daea8766e9d8bfbada31605"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3320ba068198adc144c89d6661b805acce01735b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/57f2042fd87d7ce8fc3ac8b6c176e554df68b1a7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ca53bb17f4e8232cfaece3953d3cef62c559b039"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/deffa929086d7902e30918adf3dd27ccfe9c08b1"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64398.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64398"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "ksmbd: add a permission check for FSCTL_SET_ZERO_DATA"
}