CVE-2026-64431 (GCVE-0-2026-64431)
Vulnerability from cvelistv5 – Published: 2026-07-25 08:51 – Updated: 2026-07-27 05:00
VLAI
EPSS
VEX
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.
Severity
7.8 (High)
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | |
|---|---|---|---|
| Linux | Linux |
Affected:
0a8ac0c1fa0b99a5b29002bc7f232ed7eafddef0 , < e2018628301a6d9f54e34b0cb417f1688c66df1d
(git)
Affected: 0a8ac0c1fa0b99a5b29002bc7f232ed7eafddef0 , < 5b6eedd7cc2936f9238e852b553a1b326105bde8 (git) |
|
| 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) |
{
"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"
},
{
"lessThan": "5b6eedd7cc2936f9238e852b553a1b326105bde8",
"status": "affected",
"version": "0a8ac0c1fa0b99a5b29002bc7f232ed7eafddef0",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/ntfs/index.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "7.1"
},
{
"lessThan": "7.1",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.4",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2-rc3",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"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",
"versionStartIncluding": "7.1",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"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"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/e2018628301a6d9f54e34b0cb417f1688c66df1d"
},
{
"url": "https://git.kernel.org/stable/c/5b6eedd7cc2936f9238e852b553a1b326105bde8"
}
],
"title": "ntfs: avoid calling post_write_mst_fixup() for invalid index_block",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"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"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"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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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
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
| Author | Source | Type | Date | Other |
|---|
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.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
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