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CVE-2026-72196 (GCVE-0-2026-72196)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:53 – Updated: 2026-08-17 05:41
VLAI
Title
fs/ntfs3: bound copy_lcns dp->page_lcns[] index in analysis pass
Summary
In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: bound copy_lcns dp->page_lcns[] index in analysis pass In log_replay()'s analysis pass, after find_dp() returns a valid DIR_PAGE_ENTRY for the (target_attr, target_vcn) tuple, the copy_lcns block walks lrh->lcns_follow further entries: t16 = le16_to_cpu(lrh->lcns_follow); for (i = 0; i < t16; i++) { size_t j = (size_t)(le64_to_cpu(lrh->target_vcn) - le64_to_cpu(dp->vcn)); dp->page_lcns[j + i] = lrh->page_lcns[i]; } find_dp() only validates that target_vcn falls within [dp->vcn, dp->vcn + dp->lcns_follow), i.e., that the FIRST cluster is covered. The walk through the further entries is not bounded against dp->lcns_follow. For a malformed LRH where target_vcn = dp->vcn + dp->lcns_follow - 1 and lrh->lcns_follow > 1, the i > 0 writes overflow the dp's allocated page_lcns[] array. Add the missing j + lrh->lcns_follow <= dp->lcns_follow guard. Reproduced under UML+KASAN on mainline 8d90b09e6741 as a slab-out-of-bounds write of size 8 from log_replay+0x68d4 on the mount path. This is distinct from Pavitra Jha's 2026-05-02 patch ("fs/ntfs3: validate lcns_follow in log_replay conversion", <20260502154252.164586-1-jhapavitra98@gmail.com>) which addresses the separate version-0 dirty-page-table conversion path's memmove(&dp->vcn, ...) call. The two fixes are complementary; both should land. [almaz.alexandrovich@paragon-software.com: clang-formatted the changes, fixed conflicts]
Severity
8.4 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: b46acd6a6a627d876898e1c84d3f84902264b445 , < 9b3d8cc9d54fcded4de51b2b1026ae7182512077 (git)
Affected: b46acd6a6a627d876898e1c84d3f84902264b445 , < 9b7c28d8c61bdb041936222a09a708531a1c2921 (git)
Affected: b46acd6a6a627d876898e1c84d3f84902264b445 , < 0f13e823bf86bd1800168ea0bb5bca8b8500a81c (git)
Affected: b46acd6a6a627d876898e1c84d3f84902264b445 , < d240cd98f5f7b65c90f6b2b6abe3232ccdc405ab (git)
Affected: b46acd6a6a627d876898e1c84d3f84902264b445 , < 49c86dae0c0ccb8d98ddcdc46987259389c816dd (git)
Affected: b46acd6a6a627d876898e1c84d3f84902264b445 , < 5e7b598660cfa8e5af172cf4c65cffc126333307 (git)
guessed Create a notification for this product.
Linux Linux Affected: 5.15
Unaffected: 0 , < 5.15 (semver)
Unaffected: 6.1.178 , ≤ 6.1.* (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs/ntfs3: bound copy_lcns dp-\u003epage_lcns[] index in analysis pass\n\nIn log_replay()\u0027s analysis pass, after find_dp() returns a\nvalid DIR_PAGE_ENTRY for the (target_attr, target_vcn) tuple,\nthe copy_lcns block walks lrh-\u003elcns_follow further entries:\n\n\tt16 = le16_to_cpu(lrh-\u003elcns_follow);\n\tfor (i = 0; i \u003c t16; i++) {\n\t    size_t j = (size_t)(le64_to_cpu(lrh-\u003etarget_vcn) -\n\t                        le64_to_cpu(dp-\u003evcn));\n\t    dp-\u003epage_lcns[j + i] = lrh-\u003epage_lcns[i];\n\t}\n\nfind_dp() only validates that target_vcn falls within\n[dp-\u003evcn, dp-\u003evcn + dp-\u003elcns_follow), i.e., that the FIRST\ncluster is covered.  The walk through the further entries is\nnot bounded against dp-\u003elcns_follow.  For a malformed LRH\nwhere target_vcn = dp-\u003evcn + dp-\u003elcns_follow - 1 and\nlrh-\u003elcns_follow \u003e 1, the i \u003e 0 writes overflow the dp\u0027s\nallocated page_lcns[] array.\n\nAdd the missing j + lrh-\u003elcns_follow \u003c= dp-\u003elcns_follow guard.\n\nReproduced under UML+KASAN on mainline 8d90b09e6741 as a\nslab-out-of-bounds write of size 8 from log_replay+0x68d4 on\nthe mount path.\n\nThis is distinct from Pavitra Jha\u0027s 2026-05-02 patch\n(\"fs/ntfs3: validate lcns_follow in log_replay conversion\",\n\u003c20260502154252.164586-1-jhapavitra98@gmail.com\u003e) which\naddresses the separate version-0 dirty-page-table conversion\npath\u0027s memmove(\u0026dp-\u003evcn, ...) call.  The two fixes are\ncomplementary; both should land.\n\n[almaz.alexandrovich@paragon-software.com: clang-formatted the changes,\nfixed conflicts]"
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              "value": "AV:L - The flaw is in ntfs3 log_replay() during mount when parsing a crafted $LogFile on a block device; exploitation requires a local mount syscall or auto-mount of attacker-supplied removable media, not delivery through a network-facing kernel protocol handler.\nAC:L - An attacker fully controls malicious NTFS $LogFile journal fields (target_vcn, lcns_follow, page_lcns) and can craft the dirty-page-table state; KASAN reliably reproduced the slab OOB write on mount with no races or attacker-uncontrollable conditions.\nPR:N - No account or privileges on the victim are needed when a crafted NTFS volume on removable media is auto-mounted by udisks/systemd as root; alternatively an unprivileged user can trigger replay via user-namespace mount with CAP_SYS_ADMIN.\nUI:N - Once an attacker mounts or causes mount of a crafted NTFS image, log_replay() runs automatically inside ntfs_fill_super() with no further user interaction; the vulnerable copy_lcns path is reached during standard journal analysis on every affected mount attempt.\nS:U - Exploitation corrupts kernel heap memory during ntfs3 journal replay in the mounting process context; impact is privilege escalation within the same kernel/host security boundary, not a VM-guest-to-host or IOMMU boundary crossing.\nC:H - KASAN confirmed a slab out-of-bounds write of 8 bytes past dp-\u003epage_lcns[] in a kmalloc-backed DIR_PAGE_ENTRY; such heap corruption can overwrite adjacent slab objects and be groomed into arbitrary kernel memory read primitives.\nI:H - The bug is an out-of-bounds write into kernel heap metadata or adjacent objects beyond the allocated page_lcns[] array; per kernel guidance OOB writes enable controlled heap corruption paths toward arbitrary kernel writes and privilege escalation.\nA:H - KASAN reported slab-out-of-bounds write from log_replay() on mount; heap corruption during journal replay can cause immediate kernel oops/panic and is repeatable on each mount of a malicious NTFS volume, constituting high availability impact."
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The walk through the further entries is\\nnot bounded against dp-\u003elcns_follow.  For a malformed LRH\\nwhere target_vcn = dp-\u003evcn + dp-\u003elcns_follow - 1 and\\nlrh-\u003elcns_follow \u003e 1, the i \u003e 0 writes overflow the dp\u0027s\\nallocated page_lcns[] array.\\n\\nAdd the missing j + lrh-\u003elcns_follow \u003c= dp-\u003elcns_follow guard.\\n\\nReproduced under UML+KASAN on mainline 8d90b09e6741 as a\\nslab-out-of-bounds write of size 8 from log_replay+0x68d4 on\\nthe mount path.\\n\\nThis is distinct from Pavitra Jha\u0027s 2026-05-02 patch\\n(\\\"fs/ntfs3: validate lcns_follow in log_replay conversion\\\",\\n\u003c20260502154252.164586-1-jhapavitra98@gmail.com\u003e) which\\naddresses the separate version-0 dirty-page-table conversion\\npath\u0027s memmove(\u0026dp-\u003evcn, ...) call.  The two fixes are\\ncomplementary; both should land.\\n\\n[almaz.alexandrovich@paragon-software.com: clang-formatted the changes,\\nfixed conflicts]\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/ntfs3/fslog.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"b46acd6a6a627d876898e1c84d3f84902264b445\",\"lessThan\":\"9b3d8cc9d54fcded4de51b2b1026ae7182512077\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"b46acd6a6a627d876898e1c84d3f84902264b445\",\"lessThan\":\"9b7c28d8c61bdb041936222a09a708531a1c2921\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"b46acd6a6a627d876898e1c84d3f84902264b445\",\"lessThan\":\"0f13e823bf86bd1800168ea0bb5bca8b8500a81c\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"b46acd6a6a627d876898e1c84d3f84902264b445\",\"lessThan\":\"d240cd98f5f7b65c90f6b2b6abe3232ccdc405ab\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"b46acd6a6a627d876898e1c84d3f84902264b445\",\"lessThan\":\"49c86dae0c0ccb8d98ddcdc46987259389c816dd\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"b46acd6a6a627d876898e1c84d3f84902264b445\",\"lessThan\":\"5e7b598660cfa8e5af172cf4c65cffc126333307\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/ntfs3/fslog.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"5.15\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"5.15\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.178\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.145\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.97\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.40\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.5\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"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:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":8.4,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.5,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0f13e823bf86bd1800168ea0bb5bca8b8500a81c\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/49c86dae0c0ccb8d98ddcdc46987259389c816dd\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/5e7b598660cfa8e5af172cf4c65cffc126333307\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9b3d8cc9d54fcded4de51b2b1026ae7182512077\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9b7c28d8c61bdb041936222a09a708531a1c2921\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d240cd98f5f7b65c90f6b2b6abe3232ccdc405ab\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-18T15:33:19+00:00",
      "cve": "CVE-2026-72196",
      "id": "CVE-2026-72196",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: fs/ntfs3: bound copy_lcns dp-\u003epage_lcns[] index in analysis pass",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72196.json",
      "version": "3"
    }
  }
}



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