{
  "cveId": "CVE-2026-64398",
  "url": "https://patchblox.com/security/cve/CVE-2026-64398",
  "summary": "CVE-2026-64398 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-64398, released July 26, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  ksmbd: add a permission check for FSCTL_SET_ZERO...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  ksmbd: add a permission check for FSCTL_SET_ZERO_DATA  FSCTL_SET_ZERO_DATA in smb2_ioctl() destroys file data via ksmbd_vfs_zero_data() -\u003E vfs_fallocate(PUNCH_HOLE/ZERO_RANGE) after checking only the share-level KSMBD_TREE_CONN_FLAG_WRITABLE, with no per-handle access check. A handle opened with only FILE_WRITE_ATTRIBUTES still yields an FMODE_WRITE filp (FILE_WRITE_ATTRIBUTES is part of FILE_WRITE_DESIRE_ACCESS_LE, so smb2_create_open_flags() opens it O_WRONLY), so the vfs_fallocate FMODE_WRITE check does not stop it; only the missing fp-\u003Edaccess gate would. Reproduced on mainline 7.1-rc7 with KASAN by an authenticated SMB client: a FILE_WRITE_ATTRIBUTES-only handle zeroed 4096 bytes of file data it had no FILE_WRITE_DATA right to (6/6; a FILE_READ_DATA-only handle was correctly denied).  This is the unfixed sibling of commit cc57232cae23 (\u0022ksmbd: fix FSCTL permission bypass by adding a permission check for FSCTL_SET_SPARSE\u0022). Because SET_ZERO_DATA writes data (not an attribute), require FILE_WRITE_DATA.",
  "published": "2026-07-25T10:17:23Z",
  "severity": "high",
  "cvss": 8.1,
  "cvssVector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
  "epss": 0.00464,
  "epssPercentile": 0.40435,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "6.1.180-1",
      "fix": "DEBIAN-CVE-2026-64398",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-64398",
      "released": "2026-07-26T13:52:50Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "6.12.96-1",
      "fix": "DEBIAN-CVE-2026-64398",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-64398",
      "released": "2026-07-26T13:52:50Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.1.4-1",
      "fix": "DEBIAN-CVE-2026-64398",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-64398",
      "released": "2026-07-26T13:52:50Z"
    },
    {
      "platform": "linux",
      "product": "linux-6.12",
      "release": "Debian 12.15 (bookworm)",
      "fixedVersion": "6.12.100-1~deb12u1",
      "fix": "DEBIAN-CVE-2026-64398",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-64398",
      "released": "2026-07-26T13:52:50Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T13:06:02Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}