CVE-2026-64431

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-64431", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T15:36:31.787Z", "datePublished": "2026-07-25T08:51:07.194Z", "dateUpdated": "2026-08-17T04:55:32.047Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T04:55:32.047Z"}, "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't 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 <TASK>\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 <TASK>\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's 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": {"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"}, "scenarios": [{"lang": "en", "value": "AV:L - The malformed USA fields originate in a crafted NTFS volume, and exploitation proceeds through local file modification followed by fsync or writeback. Network file access alone cannot create the required malformed index metadata.\nAC:L - The attacker controls the index block, USA offset/count, target filename, and triggering operation; no race or condition outside attacker control is required. The usa_count underflow provides a deterministic corruption path.\nPR:L - Although a direct NTFS mount requires initial-namespace CAP_SYS_ADMIN because NTFS lacks FS_USERNS_MOUNT, delegated or automatic mounting allows an ordinary local user to reach the trigger. After mounting, only write access to the crafted file is needed and no capability check occurs.\nUI:N - In reasonable automount, delegated-mount, or fstab-user deployments, no separate victim action is required. The attacker can mount or access the volume, modify the writable file, and invoke fsync independently.\nS:U - The corruption occurs in the host kernel and compromises resources governed by that same kernel security authority. This is standard local kernel privilege escalation rather than a guest-to-host or IOMMU boundary escape.\nC:H - Unchecked USA metadata causes substantial out-of-bounds reads, and the accompanying kernel heap corruption can be leveraged to disclose arbitrary kernel memory. The reads are not confined to a small bounded value.\nI:H - An underflowed usa_count produces up to 65,535 two-byte writes at 512-byte intervals, spanning roughly 32 MiB beyond the index-block allocation. Attacker-controlled initial source values and heap grooming make control-flow hijacking or arbitrary kernel modification defensible.\nA:H - The extensive out-of-bounds access can corrupt unrelated kernel objects or access invalid memory, causing an oops, panic, or system-wide failure. The trigger is repeatable through local filesystem operations."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/ntfs/index.c"], "versions": [{"version": "0a8ac0c1fa0b99a5b29002bc7f232ed7eafddef0", "lessThan": "e2018628301a6d9f54e34b0cb417f1688c66df1d", "status": "affected", "versionType": "git"}, {"version": "0a8ac0c1fa0b99a5b29002bc7f232ed7eafddef0", "lessThan": "5b6eedd7cc2936f9238e852b553a1b326105bde8", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/ntfs/index.c"], "versions": [{"version": "7.1", "status": "affected"}, {"version": "0", "lessThan": "7.1", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.4", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.1", "versionEndExcluding": "7.1.4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.1", "versionEndExcluding": "7.2"}]}]}], "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"}}}}

{}

{"affected": [{"affectedData": [{"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", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "7D22B17B-4F96-43BE-835F-3A80228838B0", "versionEndExcluding": "7.1.4", "versionStartIncluding": "7.1", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.2:rc1:*:*:*:*:*:*", "matchCriteriaId": "5E8B9085-7ADB-4A05-89EF-12949B6A0509", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.2:rc2:*:*:*:*:*:*", "matchCriteriaId": "1FC0D50D-9D58-4947-A197-A5A3FF07E7E3", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "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't 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 <TASK>\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 <TASK>\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's 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."}], "id": "CVE-2026-64431", "lastModified": "2026-09-03T18:29:10.100", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-07-25T10:17:27.327", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/5b6eedd7cc2936f9238e852b553a1b326105bde8"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/e2018628301a6d9f54e34b0cb417f1688c66df1d"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-787"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: ntfs: avoid calling post_write_mst_fixup() for invalid index_block", "id": "2507261", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2507261"}, "csaw": false, "cwe": "CWE-787", "details": ["A flaw was found in the Linux kernel's NTFS file system driver. A remote attacker could exploit this vulnerability by providing a specially crafted NTFS image, leading to out-of-bounds memory access. This memory corruption can cause the system to crash, resulting in a denial of service."], "name": "CVE-2026-64431", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-07-25T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-64431\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-64431\nhttps://lore.kernel.org/linux-cve-announce/2026072536-CVE-2026-64431-3f8c@gregkh/T"]}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[0a8ac0c1fa0b99a5b29002bc7f232ed7eafddef0,e2018628301a6d9f54e34b0cb417f1688c66df1d)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[0a8ac0c1fa0b99a5b29002bc7f232ed7eafddef0,5b6eedd7cc2936f9238e852b553a1b326105bde8)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "7.1"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,7.1)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.1.4,7.2.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.2-rc3,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-07-25T18:00:05.885550+00:00", "updated": "2026-08-04T14:30:10.634363+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"]}