CVE-2026-72209 (GCVE-0-2026-72209)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:54 – Updated: 2026-08-17 05:41
VLAI
Title
ntfs: validate attribute values on lookup
Summary
In the Linux kernel, the following vulnerability has been resolved: ntfs: validate attribute values on lookup ntfs_attr_find() and ntfs_external_attr_find() check that generic resident attribute values fit in their attribute records and that fixed-size resident values are large enough. For variable-length resident formats, however, the fixed part is not enough: embedded length fields can still point callers past the resident value. A crafted image can set a small resident $FILE_NAME value_length while leaving file_name_length large. Callers then trust file_name_length and read past the resident value when converting or comparing the name. This was reproduced with a crafted image under KASAN as a slab-out-of-bounds read from the kmalloc-1k MFT record copy. The stack included ntfs_lookup(), ntfs_iget(), ntfs_read_locked_inode(), ntfs_attr_name_get(), ntfs_ucstonls(), and utf16s_to_utf8s(). Add a shared attribute value validator and use it before a lookup path can return an attribute, including the AT_UNUSED enumeration case where callers inspect returned attributes directly. The helper validates resident value bounds, minimum resident value sizes, variable-length $FILE_NAME fields, and non-resident mapping-pairs metadata that was previously checked separately in both lookup paths. This also preserves the intended resident @val matching semantics in the external attribute lookup path. The old duplicated validation block overwrote the actual resident value length with the type-specific minimum length before comparing @val, so variable-length resident values could fail to match even when the bytes were identical. Keep the comparison on the actual value length, and make ntfs_attrlist_entry_add() compare resident attributes with lowest_vcn zero instead of reading the non-resident union member after a successful resident match. Reject non-resident $FILE_NAME records too: the format requires $FILE_NAME to be resident and callers treat returned records as resident.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/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: 6ceb4cc81ef3409ff79dcb959771f9110787397a , < e4c36dfac57a7261e9aeb0f3a7f30944a8aefb56 (git)
Affected: 6ceb4cc81ef3409ff79dcb959771f9110787397a , < d5803e3345dae9c6470bb61869885236276b9a35 (git)
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Linux Linux Affected: 7.1
Unaffected: 0 , < 7.1 (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ntfs/attrib.c",
            "fs/ntfs/attrlist.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "lessThan": "e4c36dfac57a7261e9aeb0f3a7f30944a8aefb56",
              "status": "affected",
              "version": "6ceb4cc81ef3409ff79dcb959771f9110787397a",
              "versionType": "git"
            },
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              "status": "affected",
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              "versionType": "git"
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          "product": "Linux",
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            "fs/ntfs/attrlist.c"
          ],
          "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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              "version": "0",
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              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.5",
                  "versionStartIncluding": "7.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "7.1",
                  "vulnerable": true
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              ],
              "negate": false,
              "operator": "OR"
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          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nntfs: validate attribute values on lookup\n\nntfs_attr_find() and ntfs_external_attr_find() check that generic\nresident attribute values fit in their attribute records and that\nfixed-size resident values are large enough. For variable-length resident\nformats, however, the fixed part is not enough: embedded length fields\ncan still point callers past the resident value.\n\nA crafted image can set a small resident $FILE_NAME value_length while\nleaving file_name_length large. Callers then trust file_name_length and\nread past the resident value when converting or comparing the name. This\nwas reproduced with a crafted image under KASAN as a slab-out-of-bounds\nread from the kmalloc-1k MFT record copy. The stack included\nntfs_lookup(), ntfs_iget(), ntfs_read_locked_inode(), ntfs_attr_name_get(),\nntfs_ucstonls(), and utf16s_to_utf8s().\n\nAdd a shared attribute value validator and use it before a lookup path\ncan return an attribute, including the AT_UNUSED enumeration case where\ncallers inspect returned attributes directly. The helper validates\nresident value bounds, minimum resident value sizes, variable-length\n$FILE_NAME fields, and non-resident mapping-pairs metadata that was\npreviously checked separately in both lookup paths.\n\nThis also preserves the intended resident @val matching semantics in the\nexternal attribute lookup path. The old duplicated validation block\noverwrote the actual resident value length with the type-specific minimum\nlength before comparing @val, so variable-length resident values could\nfail to match even when the bytes were identical. Keep the comparison on\nthe actual value length, and make ntfs_attrlist_entry_add() compare\nresident attributes with lowest_vcn zero instead of reading the\nnon-resident union member after a successful resident match.\n\nReject non-resident $FILE_NAME records too: the format requires\n$FILE_NAME to be resident and callers treat returned records as resident."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - NTFS registers ntfs_export_ops; remote nfsd/ksmbd VFS lookups on an exported crafted NTFS volume reach ntfs_lookup\u2192ntfs_iget\u2192ntfs_read_locked_inode\u2192ntfs_attr_name_get without local syscall access.\nAC:L - The attacker fully controls on-disk $FILE_NAME metadata (small resident value_length with large file_name_length) in a crafted image; the fix commit reproduced the slab OOB read via ntfs_lookup deterministically with no races.\nPR:N - Triggering needs only read access to mounted NTFS content (e.g., authenticated or guest NFS/SMB client on an exported share) or supplying removable media later mounted by the host; no init-namespace root or CAP_SYS_ADMIN on the lookup path.\nUI:N - Once a crafted NTFS volume is mounted and exported (or loop-mounted in a user namespace), normal remote lookups/opens reach the vulnerable attribute parsing without further victim clicks or cooperative actions.\nS:U - The slab out-of-bounds read and potential kernel crash stay within the mounting host kernel authority; this is standard filesystem parsing exploitation, not a VM escape, IOMMU bypass, or cross-sandbox scope change.\nC:H - Callers trust inflated file_name_length and ntfs_ucstonls/utf16s_to_utf8s read past the resident $FILE_NAME value in the kmalloc-1k MFT record copy, disclosing adjacent slab heap memory beyond a few bytes.\nI:H - Attacker-controlled file_name_length drives kernel parsing of forged resident metadata and adjacent slab contents; per kernel CNA guidance, this memory-corruption class can be leveraged for arbitrary kernel modification or control-flow hijack beyond the immediate read.\nA:H - KASAN reports slab-out-of-bounds read from the MFT record copy on lookup; reading past the resident $FILE_NAME value can oops or panic the kernel when accessing invalid adjacent memory."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:41:36.117Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e4c36dfac57a7261e9aeb0f3a7f30944a8aefb56"
        },
        {
          "url": "https://git.kernel.org/stable/c/d5803e3345dae9c6470bb61869885236276b9a35"
        }
      ],
      "title": "ntfs: validate attribute values on lookup",
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        "engine": "bippy-1.2.0"
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    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72209",
    "datePublished": "2026-08-15T05:54:04.772Z",
    "dateReserved": "2026-08-09T03:40:39.912Z",
    "dateUpdated": "2026-08-17T05:41:36.117Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-72209",
      "date": "2026-08-27",
      "epss": "0.00516",
      "percentile": "0.41771"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-72209\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-08-15T06:21:39.607\",\"lastModified\":\"2026-08-17T06:18:21.803\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nntfs: validate attribute values on lookup\\n\\nntfs_attr_find() and ntfs_external_attr_find() check that generic\\nresident attribute values fit in their attribute records and that\\nfixed-size resident values are large enough. For variable-length resident\\nformats, however, the fixed part is not enough: embedded length fields\\ncan still point callers past the resident value.\\n\\nA crafted image can set a small resident $FILE_NAME value_length while\\nleaving file_name_length large. Callers then trust file_name_length and\\nread past the resident value when converting or comparing the name. This\\nwas reproduced with a crafted image under KASAN as a slab-out-of-bounds\\nread from the kmalloc-1k MFT record copy. The stack included\\nntfs_lookup(), ntfs_iget(), ntfs_read_locked_inode(), ntfs_attr_name_get(),\\nntfs_ucstonls(), and utf16s_to_utf8s().\\n\\nAdd a shared attribute value validator and use it before a lookup path\\ncan return an attribute, including the AT_UNUSED enumeration case where\\ncallers inspect returned attributes directly. The helper validates\\nresident value bounds, minimum resident value sizes, variable-length\\n$FILE_NAME fields, and non-resident mapping-pairs metadata that was\\npreviously checked separately in both lookup paths.\\n\\nThis also preserves the intended resident @val matching semantics in the\\nexternal attribute lookup path. The old duplicated validation block\\noverwrote the actual resident value length with the type-specific minimum\\nlength before comparing @val, so variable-length resident values could\\nfail to match even when the bytes were identical. Keep the comparison on\\nthe actual value length, and make ntfs_attrlist_entry_add() compare\\nresident attributes with lowest_vcn zero instead of reading the\\nnon-resident union member after a successful resident match.\\n\\nReject non-resident $FILE_NAME records too: the format requires\\n$FILE_NAME to be resident and callers treat returned records as resident.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/ntfs/attrib.c\",\"fs/ntfs/attrlist.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6ceb4cc81ef3409ff79dcb959771f9110787397a\",\"lessThan\":\"e4c36dfac57a7261e9aeb0f3a7f30944a8aefb56\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6ceb4cc81ef3409ff79dcb959771f9110787397a\",\"lessThan\":\"d5803e3345dae9c6470bb61869885236276b9a35\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/ntfs/attrib.c\",\"fs/ntfs/attrlist.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\":\"7.1.5\",\"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:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":9.8,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/d5803e3345dae9c6470bb61869885236276b9a35\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e4c36dfac57a7261e9aeb0f3a7f30944a8aefb56\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-18T16:28:58+00:00",
      "cve": "CVE-2026-72209",
      "id": "CVE-2026-72209",
      "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: ntfs: validate attribute values on lookup",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72209.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-21T00:42:29Z",
      "cve": "CVE-2026-72209",
      "id": "CVE-2026-72209",
      "initial_release_date": "2026-08-21T00:42:29Z",
      "product_status:known_not_affected": "284",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-72209",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-72209.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.

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  • 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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  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
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  • 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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