{
  "cveId": "CVE-2026-64431",
  "url": "https://patchblox.com/security/cve/CVE-2026-64431",
  "summary": "CVE-2026-64431 is fixed in linux on 1 platform by DEBIAN-CVE-2026-64431 (version 7.1.4-1), released August 7, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  ntfs: avoid calling post_write_mst_fixup() for i...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  ntfs: avoid calling post_write_mst_fixup() for invalid index_block  ntfs_icx_ib_sync_write() calls post_write_mst_fixup() when ntfs_ib_write() returns an error, intending to restore the buffer after a failed write.  However, ntfs_ib_write() returns an error immediately if pre_write_mst_fixup() validation fails. The caller, ntfs_icx_ib_sync_write(), interprets any error as a write failure requiring rollback. It does not differentiate between I/O errors and validation failures, and calls post_write_mst_fixup() anyway.  Since post_write_mst_fixup() assumes that the index_block contents is correct, it doesn\u0027t perform the boundary checks, which results in out-of-bounds memory access.  An attacker can craft a malicious NTFS image with:   - large index_block.usa_ofs offset, pointing outside the ntfs_record   - index_block.usa_count = 0, causing integer underflow   - or index_block.usa_count larger than actual number of sectors in the     ntfs_record, causing out-of-bounds access  KASAN reports describing the memory corruption:   ==================================================================   BUG: KASAN: slab-out-of-bounds in post_write_mst_fixup\u002B0x19c/0x1d0   Read of size 2 at addr ffff8881586c9018 by task p/9428   Call Trace:    \u003CTASK\u003E    dump_stack_lvl\u002B0x100/0x190    print_report\u002B0x139/0x4ad    ? post_write_mst_fixup\u002B0x19c/0x1d0    ? __virt_addr_valid\u002B0x262/0x500    ? post_write_mst_fixup\u002B0x19c/0x1d0    kasan_report\u002B0xe4/0x1d0    ? post_write_mst_fixup\u002B0x19c/0x1d0    post_write_mst_fixup\u002B0x19c/0x1d0    ntfs_icx_ib_sync_write\u002B0x179/0x220    ntfs_inode_sync_filename\u002B0x83d/0x1080    __ntfs_write_inode\u002B0x1049/0x1480    ntfs_file_fsync\u002B0x131/0x9b0   ==================================================================   BUG: KASAN: slab-out-of-bounds in post_write_mst_fixup\u002B0x1aa/0x1d0   Write of size 2 at addr ffff8881586c91fe by task p/9428   Call Trace:    \u003CTASK\u003E    dump_stack_lvl\u002B0x100/0x190    print_report\u002B0x139/0x4ad    ? post_write_mst_fixup\u002B0x1aa/0x1d0    ? __virt_addr_valid\u002B0x262/0x500    ? post_write_mst_fixup\u002B0x1aa/0x1d0    kasan_report\u002B0xe4/0x1d0    ? post_write_mst_fixup\u002B0x1aa/0x1d0    post_write_mst_fixup\u002B0x1aa/0x1d0    ntfs_icx_ib_sync_write\u002B0x179/0x220    ntfs_inode_sync_filename\u002B0x83d/0x1080    __ntfs_write_inode\u002B0x1049/0x1480    ntfs_file_fsync\u002B0x131/0x9b0   ==================================================================  Let\u0027s move the post_write_mst_fixup() call to ntfs_ib_write(). The ntfs_ib_write() function calls pre_write_mst_fixup() at the beginning. If the index_block contents is invalid, pre_write_mst_fixup() fails and ntfs_ib_write() returns early without calling post_write_mst_fixup() on bad index_block.",
  "published": "2026-07-25T10:17:27Z",
  "severity": "high",
  "cvss": 7.8,
  "cvssVector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
  "epss": 0.00165,
  "epssPercentile": 0.05763,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.1.4-1",
      "fix": "DEBIAN-CVE-2026-64431",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-64431",
      "released": "2026-08-07T15:22:10Z"
    }
  ],
  "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"
  }
}