{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.1.4-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "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't 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+0x19c/0x1d0   Read of size 2 at addr ffff8881586c9018 by task p/9428   Call Trace:    \u003cTASK\u003e    dump_stack_lvl+0x100/0x190    print_report+0x139/0x4ad    ? post_write_mst_fixup+0x19c/0x1d0    ? __virt_addr_valid+0x262/0x500    ? post_write_mst_fixup+0x19c/0x1d0    kasan_report+0xe4/0x1d0    ? post_write_mst_fixup+0x19c/0x1d0    post_write_mst_fixup+0x19c/0x1d0    ntfs_icx_ib_sync_write+0x179/0x220    ntfs_inode_sync_filename+0x83d/0x1080    __ntfs_write_inode+0x1049/0x1480    ntfs_file_fsync+0x131/0x9b0   ==================================================================   BUG: KASAN: slab-out-of-bounds in post_write_mst_fixup+0x1aa/0x1d0   Write of size 2 at addr ffff8881586c91fe by task p/9428   Call Trace:    \u003cTASK\u003e    dump_stack_lvl+0x100/0x190    print_report+0x139/0x4ad    ? post_write_mst_fixup+0x1aa/0x1d0    ? __virt_addr_valid+0x262/0x500    ? post_write_mst_fixup+0x1aa/0x1d0    kasan_report+0xe4/0x1d0    ? post_write_mst_fixup+0x1aa/0x1d0    post_write_mst_fixup+0x1aa/0x1d0    ntfs_icx_ib_sync_write+0x179/0x220    ntfs_inode_sync_filename+0x83d/0x1080    __ntfs_write_inode+0x1049/0x1480    ntfs_file_fsync+0x131/0x9b0   ==================================================================  Let's 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.",
  "id": "DEBIAN-CVE-2026-64431",
  "modified": "2026-09-14T16:47:47.406209740Z",
  "published": "2026-07-25T10:17:27.327Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-64431"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-64431"
  ]
}