CVE-2026-64431 (GCVE-0-2026-64431)

Vulnerability from cvelistv5 – Published: 2026-07-25 08:51 – Updated: 2026-07-27 05:00
VLAI
Title
ntfs: avoid calling post_write_mst_fixup() for invalid index_block
Summary
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: <TASK> 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: <TASK> 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.
Assigner
Impacted products
Vendor Product Version
Linux Linux Affected: 0a8ac0c1fa0b99a5b29002bc7f232ed7eafddef0 , < e2018628301a6d9f54e34b0cb417f1688c66df1d (git)
Affected: 0a8ac0c1fa0b99a5b29002bc7f232ed7eafddef0 , < 5b6eedd7cc2936f9238e852b553a1b326105bde8 (git)
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Linux Linux Affected: 7.1
Unaffected: 0 , < 7.1 (semver)
Unaffected: 7.1.4 , ≤ 7.1.* (semver)
Unaffected: 7.2-rc3 , ≤ * (original_commit_for_fix)
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Show details on NVD website

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ntfs/index.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e2018628301a6d9f54e34b0cb417f1688c66df1d",
              "status": "affected",
              "version": "0a8ac0c1fa0b99a5b29002bc7f232ed7eafddef0",
              "versionType": "git"
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              "status": "affected",
              "version": "0a8ac0c1fa0b99a5b29002bc7f232ed7eafddef0",
              "versionType": "git"
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          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/ntfs/index.c"
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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": "7.1"
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
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            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2-rc3",
              "versionType": "original_commit_for_fix"
            }
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      "cpeApplicability": [
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              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.4",
                  "versionStartIncluding": "7.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2-rc3",
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nntfs: avoid calling post_write_mst_fixup() for invalid index_block\n\nntfs_icx_ib_sync_write() calls post_write_mst_fixup() when ntfs_ib_write()\nreturns an error, intending to restore the buffer after a failed write.\n\nHowever, ntfs_ib_write() returns an error immediately if\npre_write_mst_fixup() validation fails. The caller,\nntfs_icx_ib_sync_write(), interprets any error as a write failure\nrequiring rollback. It does not differentiate between I/O errors and\nvalidation failures, and calls post_write_mst_fixup() anyway.\n\nSince post_write_mst_fixup() assumes that the index_block contents is\ncorrect, it doesn\u0027t perform the boundary checks, which results in\nout-of-bounds memory access.\n\nAn attacker can craft a malicious NTFS image with:\n  - large index_block.usa_ofs offset, pointing outside the ntfs_record\n  - index_block.usa_count = 0, causing integer underflow\n  - or index_block.usa_count larger than actual number of sectors in the\n    ntfs_record, causing out-of-bounds access\n\nKASAN reports describing the memory corruption:\n  ==================================================================\n  BUG: KASAN: slab-out-of-bounds in post_write_mst_fixup+0x19c/0x1d0\n  Read of size 2 at addr ffff8881586c9018 by task p/9428\n  Call Trace:\n   \u003cTASK\u003e\n   dump_stack_lvl+0x100/0x190\n   print_report+0x139/0x4ad\n   ? post_write_mst_fixup+0x19c/0x1d0\n   ? __virt_addr_valid+0x262/0x500\n   ? post_write_mst_fixup+0x19c/0x1d0\n   kasan_report+0xe4/0x1d0\n   ? post_write_mst_fixup+0x19c/0x1d0\n   post_write_mst_fixup+0x19c/0x1d0\n   ntfs_icx_ib_sync_write+0x179/0x220\n   ntfs_inode_sync_filename+0x83d/0x1080\n   __ntfs_write_inode+0x1049/0x1480\n   ntfs_file_fsync+0x131/0x9b0\n  ==================================================================\n  BUG: KASAN: slab-out-of-bounds in post_write_mst_fixup+0x1aa/0x1d0\n  Write of size 2 at addr ffff8881586c91fe by task p/9428\n  Call Trace:\n   \u003cTASK\u003e\n   dump_stack_lvl+0x100/0x190\n   print_report+0x139/0x4ad\n   ? post_write_mst_fixup+0x1aa/0x1d0\n   ? __virt_addr_valid+0x262/0x500\n   ? post_write_mst_fixup+0x1aa/0x1d0\n   kasan_report+0xe4/0x1d0\n   ? post_write_mst_fixup+0x1aa/0x1d0\n   post_write_mst_fixup+0x1aa/0x1d0\n   ntfs_icx_ib_sync_write+0x179/0x220\n   ntfs_inode_sync_filename+0x83d/0x1080\n   __ntfs_write_inode+0x1049/0x1480\n   ntfs_file_fsync+0x131/0x9b0\n  ==================================================================\n\nLet\u0027s move the post_write_mst_fixup() call to ntfs_ib_write().\nThe ntfs_ib_write() function calls pre_write_mst_fixup() at the beginning.\nIf the index_block contents is invalid, pre_write_mst_fixup() fails and\nntfs_ib_write() returns early without calling post_write_mst_fixup() on\nbad index_block."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-27T05:00:52.351Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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        {
          "url": "https://git.kernel.org/stable/c/e2018628301a6d9f54e34b0cb417f1688c66df1d"
        },
        {
          "url": "https://git.kernel.org/stable/c/5b6eedd7cc2936f9238e852b553a1b326105bde8"
        }
      ],
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64431",
    "datePublished": "2026-07-25T08:51:07.194Z",
    "dateReserved": "2026-07-19T15:36:31.787Z",
    "dateUpdated": "2026-07-27T05:00:52.351Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
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    "epss": {
      "cve": "CVE-2026-64431",
      "date": "2026-07-26",
      "epss": "0.00159",
      "percentile": "0.05456"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-64431\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-07-25T10:17:27.327\",\"lastModified\":\"2026-07-27T05:16:49.397\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nntfs: avoid calling post_write_mst_fixup() for invalid index_block\\n\\nntfs_icx_ib_sync_write() calls post_write_mst_fixup() when ntfs_ib_write()\\nreturns an error, intending to restore the buffer after a failed write.\\n\\nHowever, ntfs_ib_write() returns an error immediately if\\npre_write_mst_fixup() validation fails. The caller,\\nntfs_icx_ib_sync_write(), interprets any error as a write failure\\nrequiring rollback. It does not differentiate between I/O errors and\\nvalidation failures, and calls post_write_mst_fixup() anyway.\\n\\nSince post_write_mst_fixup() assumes that the index_block contents is\\ncorrect, it doesn\u0027t perform the boundary checks, which results in\\nout-of-bounds memory access.\\n\\nAn attacker can craft a malicious NTFS image with:\\n  - large index_block.usa_ofs offset, pointing outside the ntfs_record\\n  - index_block.usa_count = 0, causing integer underflow\\n  - or index_block.usa_count larger than actual number of sectors in the\\n    ntfs_record, causing out-of-bounds access\\n\\nKASAN reports describing the memory corruption:\\n  ==================================================================\\n  BUG: KASAN: slab-out-of-bounds in post_write_mst_fixup+0x19c/0x1d0\\n  Read of size 2 at addr ffff8881586c9018 by task p/9428\\n  Call Trace:\\n   \u003cTASK\u003e\\n   dump_stack_lvl+0x100/0x190\\n   print_report+0x139/0x4ad\\n   ? post_write_mst_fixup+0x19c/0x1d0\\n   ? __virt_addr_valid+0x262/0x500\\n   ? post_write_mst_fixup+0x19c/0x1d0\\n   kasan_report+0xe4/0x1d0\\n   ? post_write_mst_fixup+0x19c/0x1d0\\n   post_write_mst_fixup+0x19c/0x1d0\\n   ntfs_icx_ib_sync_write+0x179/0x220\\n   ntfs_inode_sync_filename+0x83d/0x1080\\n   __ntfs_write_inode+0x1049/0x1480\\n   ntfs_file_fsync+0x131/0x9b0\\n  ==================================================================\\n  BUG: KASAN: slab-out-of-bounds in post_write_mst_fixup+0x1aa/0x1d0\\n  Write of size 2 at addr ffff8881586c91fe by task p/9428\\n  Call Trace:\\n   \u003cTASK\u003e\\n   dump_stack_lvl+0x100/0x190\\n   print_report+0x139/0x4ad\\n   ? post_write_mst_fixup+0x1aa/0x1d0\\n   ? __virt_addr_valid+0x262/0x500\\n   ? post_write_mst_fixup+0x1aa/0x1d0\\n   kasan_report+0xe4/0x1d0\\n   ? post_write_mst_fixup+0x1aa/0x1d0\\n   post_write_mst_fixup+0x1aa/0x1d0\\n   ntfs_icx_ib_sync_write+0x179/0x220\\n   ntfs_inode_sync_filename+0x83d/0x1080\\n   __ntfs_write_inode+0x1049/0x1480\\n   ntfs_file_fsync+0x131/0x9b0\\n  ==================================================================\\n\\nLet\u0027s move the post_write_mst_fixup() call to ntfs_ib_write().\\nThe ntfs_ib_write() function calls pre_write_mst_fixup() at the beginning.\\nIf the index_block contents is invalid, pre_write_mst_fixup() fails and\\nntfs_ib_write() returns early without calling post_write_mst_fixup() on\\nbad index_block.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/ntfs/index.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"0a8ac0c1fa0b99a5b29002bc7f232ed7eafddef0\",\"lessThan\":\"e2018628301a6d9f54e34b0cb417f1688c66df1d\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"0a8ac0c1fa0b99a5b29002bc7f232ed7eafddef0\",\"lessThan\":\"5b6eedd7cc2936f9238e852b553a1b326105bde8\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/ntfs/index.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"7.1\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"7.1\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.4\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2-rc3\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/5b6eedd7cc2936f9238e852b553a1b326105bde8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e2018628301a6d9f54e34b0cb417f1688c66df1d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "suse_vex": {
      "aggregate_severity": "not set",
      "current_release_date": "2026-07-25T15:59:28Z",
      "cve": "CVE-2026-64431",
      "id": "CVE-2026-64431",
      "initial_release_date": "2026-07-25T15:59:28Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64431",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64431.json",
      "version": "2"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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