FKIE_CVE-2026-72209

Vulnerability from fkie_nvd - Published: 2026-08-15 06:21 - Updated: 2026-08-17 06:18
Severity
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d5803e3345dae9c6470bb61869885236276b9a35
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e4c36dfac57a7261e9aeb0f3a7f30944a8aefb56
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "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": [
            {
              "lessThan": "e4c36dfac57a7261e9aeb0f3a7f30944a8aefb56",
              "status": "affected",
              "version": "6ceb4cc81ef3409ff79dcb959771f9110787397a",
              "versionType": "git"
            },
            {
              "lessThan": "d5803e3345dae9c6470bb61869885236276b9a35",
              "status": "affected",
              "version": "6ceb4cc81ef3409ff79dcb959771f9110787397a",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "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": [
            {
              "status": "affected",
              "version": "7.1"
            },
            {
              "lessThan": "7.1",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "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."
    }
  ],
  "id": "CVE-2026-72209",
  "lastModified": "2026-08-17T06:18:21.803",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-08-15T06:21:39.607",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d5803e3345dae9c6470bb61869885236276b9a35"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e4c36dfac57a7261e9aeb0f3a7f30944a8aefb56"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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