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fs/ntfs3: fix out-of-bounds read of INDEX_ROOT in reparse/objid init

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: fix out-of-bounds read of INDEX_ROOT in reparse/objid init ntfs_reparse_init() and ntfs_objid_init() parse the index root of the $Extend/$Reparse and $Extend/$ObjId metafiles (the INDEX_ROOT attributes named $R and $O). They read its type and rule fields through resident_data(), which does not check that the resident attribute is large enough to hold them. mi_enum_attr() accepts a resident attribute with data_off == asize and data_size == 0. For such an attribute placed last in its MFT record, resident_data() returns a pointer to the end of the record_size buffer, so reading root->type / root->rule reads past the allocation. Use resident_data_ex(attr, sizeof(struct INDEX_ROOT)) and bail out when it returns NULL, as ntfs_security_init() already does for $SDH / $SII. The attribute is only parsed while mounting a crafted image, so this needs CAP_SYS_ADMIN. BUG: KASAN: slab-out-of-bounds in ntfs_reparse_init (fs/ntfs3/fsntfs.c:2306) Read of size 4 at addr ffff88801219dc00 by task mount ntfs_reparse_init (fs/ntfs3/fsntfs.c:2306) ntfs_fill_super (fs/ntfs3/super.c:1604) get_tree_bdev_flags (fs/super.c:1703) vfs_get_tree (fs/super.c:1758) path_mount (fs/namespace.c:4131) __x64_sys_mount (fs/namespace.c:4360)

Products
Kernel
Affected versions
Not specified
Fixed versions
5.15.221, 6.1.188, 6.12.110, 6.18.52, 6.6.157, 7.2.6
CVEs
CVE-2026-89785
Confirmed fixed CVEs
Not specified
Updated in this feed
4 Nov 2026, 15:00 UTC · Revision 1

Source evidence

fs/ntfs3: fix out-of-bounds read of INDEX_ROOT in reparse/objid init

core-osv · Original source

Published 16 Sept 2026, 08:48 UTC

In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: fix out-of-bounds read of INDEX_ROOT in reparse/objid init ntfs_reparse_init() and ntfs_objid_init() parse the index root of the $Extend/$Reparse and $Extend/$ObjId metafiles (the INDEX_ROOT attributes named $R and $O). They read its type and rule fields through resident_data(), which does not check that the resident attribute is large enough to hold them. mi_enum_attr() accepts a resident attribute with data_off == asize and data_size == 0. For such an attribute placed last in its MFT record, resident_data() returns a pointer to the end of the record_size buffer, so reading root->type / root->rule reads past the allocation. Use resident_data_ex(attr, sizeof(struct INDEX_ROOT)) and bail out when it returns NULL, as ntfs_security_init() already does for $SDH / $SII. The attribute is only parsed while mounting a crafted image, so this needs CAP_SYS_ADMIN. BUG: KASAN: slab-out-of-bounds in ntfs_reparse_init (fs/ntfs3/fsntfs.c:2306) Read of size 4 at addr ffff88801219dc00 by task mount ntfs_reparse_init (fs/ntfs3/fsntfs.c:2306) ntfs_fill_super (fs/ntfs3/super.c:1604) get_tree_bdev_flags (fs/super.c:1703) vfs_get_tree (fs/super.c:1758) path_mount (fs/namespace.c:4131) __x64_sys_mount (fs/namespace.c:4360)

osv:CVE-2026-89785

Kernel

Fixed versions: 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.52, 7.2.6

Complete source record
{
  "id": "d07ca736544a8fd2434ef1909bb36f84418dc36bab23797d9af1a7fe14417c3d",
  "url": "https://osv.dev/vulnerability/CVE-2026-89785",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "fs/ntfs3: fix out-of-bounds read of INDEX_ROOT in reparse/objid init",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: fix out-of-bounds read of INDEX_ROOT in reparse/objid init ntfs_reparse_init() and ntfs_objid_init() parse the index root of the $Extend/$Reparse and $Extend/$ObjId metafiles (the INDEX_ROOT attributes named $R and $O). They read its type and rule fields through resident_data(), which does not check that the resident attribute is large enough to hold them. mi_enum_attr() accepts a resident attribute with data_off == asize and data_size == 0. For such an attribute placed last in its MFT record, resident_data() returns a pointer to the end of the record_size buffer, so reading root->type / root->rule reads past the allocation. Use resident_data_ex(attr, sizeof(struct INDEX_ROOT)) and bail out when it returns NULL, as ntfs_security_init() already does for $SDH / $SII. The attribute is only parsed while mounting a crafted image, so this needs CAP_SYS_ADMIN. BUG: KASAN: slab-out-of-bounds in ntfs_reparse_init (fs/ntfs3/fsntfs.c:2306) Read of size 4 at addr ffff88801219dc00 by task mount ntfs_reparse_init (fs/ntfs3/fsntfs.c:2306) ntfs_fill_super (fs/ntfs3/super.c:1604) get_tree_bdev_flags (fs/super.c:1703) vfs_get_tree (fs/super.c:1758) path_mount (fs/namespace.c:4131) __x64_sys_mount (fs/namespace.c:4360)",
    "evidence": "osv:CVE-2026-89785",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.15.221",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.188",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.157",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.110",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.52",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.6",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-89785",
      "aliases": [
        "CVE-2026-89785"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "82cae269cfa953032fbb8980a7d554d60fb00b17"
                },
                {
                  "fixed": "eb80003744e32a7366a523015e4acfe0a2ac7d88"
                },
                {
                  "fixed": "bd631e2005290a55c8edda87363bc0d594c01705"
                },
                {
                  "fixed": "94fce1d3e74fe011e21f17490ba58491709fd7e5"
                },
                {
                  "fixed": "66c074eab6f966fbe48a0fc4b3a45b2a2e2df527"
                },
                {
                  "fixed": "64bb6000bfbdf241a6dd578199acd90321a4243e"
                },
                {
                  "fixed": "72caafbc95c5dca8266a942b8e96ad81d8d9adc7"
                },
                {
                  "fixed": "2064bc663f89e61b8681c1fb9d1ce445de72063d"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89785.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.15.0"
                },
                {
                  "fixed": "5.15.221"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "6.1.188"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.6.157"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.12.110"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.52"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.2.6"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89785.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:36.411210518Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/2064bc663f89e61b8681c1fb9d1ce445de72063d",
        "https://git.kernel.org/stable/c/64bb6000bfbdf241a6dd578199acd90321a4243e",
        "https://git.kernel.org/stable/c/66c074eab6f966fbe48a0fc4b3a45b2a2e2df527",
        "https://git.kernel.org/stable/c/72caafbc95c5dca8266a942b8e96ad81d8d9adc7",
        "https://git.kernel.org/stable/c/94fce1d3e74fe011e21f17490ba58491709fd7e5",
        "https://git.kernel.org/stable/c/bd631e2005290a55c8edda87363bc0d594c01705",
        "https://git.kernel.org/stable/c/eb80003744e32a7366a523015e4acfe0a2ac7d88",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89785.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-89785",
        "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/2026/89xxx/CVE-2026-89785.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-89785",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 503886,
  "published_at": "2026-09-16T08:48:23.084+00:00"
}