ntfs: validate attribute values on lookup

{
  "id": "cc986edd6cfa0ff90420f76293324c074c937d5adccacd43719a6d771f6dab46",
  "url": "https://osv.dev/vulnerability/CVE-2026-72209",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "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-sp",
    "evidence": "osv:CVE-2026-72209",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "7.1.5",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-72209",
      "aliases": [
        "CVE-2026-72209"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "6ceb4cc81ef3409ff79dcb959771f9110787397a"
                },
                {
                  "fixed": "e4c36dfac57a7261e9aeb0f3a7f30944a8aefb56"
                },
                {
                  "fixed": "d5803e3345dae9c6470bb61869885236276b9a35"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72209.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "7.1.0"
                },
                {
                  "fixed": "7.1.5"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-72209.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:32.525614104Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/d5803e3345dae9c6470bb61869885236276b9a35",
        "https://git.kernel.org/stable/c/e4c36dfac57a7261e9aeb0f3a7f30944a8aefb56",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72209.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-72209",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72209.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-72209",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 499698,
  "published_at": "2026-08-15T05:54:04.772+00:00"
}