CVE-2026-89492

Estado: RecibidaCrítica (9.8)—

In the Linux kernel, the following vulnerability has been resolved:

ocfs2: validate directory-index entry counts when reading metadata

ocfs2_validate_dx_leaf() and ocfs2_validate_dx_root() check the ECC and signature of an indexed-directory block before it reaches higher-level callers, but neither validator bounds the ocfs2_dx_entry_list counts against the capacity of the block that holds them.

ocfs2_dx_dir_search() then walks

over de_num_used entries with no bounds check. entry_list is either dx_leaf->dl_list (from ocfs2_read_dx_leaf) or, for an inline root, dx_root->dr_entries.

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A crafted on-disk image can set de_num_used (and de_count, which is the __counted_by_le() bound of de_entries) to 0xffff and make the walk read far past the end of the 4KB metadata block, giving a slab out-of-bounds read reachable from any path lookup, stat() or open() on an indexed directory once the image is mounted.

Commit 775c17386a6f ("ocfs2: validate dx_root extent list fields during block read") already bounds dr_list for the non-inline dx_root, but left the inline dr_entries path and the dx_leaf dl_list unchecked. Add the same read-time validation for both entry lists: de_count must equal the capacity of the block (ocfs2_dx_entries_per_leaf()/per_root()) and de_num_used must not exceed de_count, rejecting corrupted metadata with -EFSCORRUPTED before ocfs2_dx_dir_search() can walk an out-of-range entry array.

de_count is always written as exactly the block capacity when a leaf or inline root is formatted, so the equality check does not reject any valid image.

Found by 0sec automated security-research tooling (https://0sec.ai).

Detalles técnicos trazas, registros y código del informe original

	for (i = 0; i < le16_to_cpu(entry_list->de_num_used); i++)
		dx_entry = &entry_list->de_entries[i];

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 9.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.64%
Percentil entre todas las CVEs puntuadas: 49
Fecha de la puntuación: 5/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1190 Exploit Public-Facing Applicationinitial access85 %
Impacto principalT1005 Data from Local Systemcollection90 %
Impacto secundarioT1499.004 Application or System Exploitationimpact60 %

Vulnerabilidad remota (AV:N, PR:N, UI:N) en kernel Linux explotable al montar imagen corrupta. Impacto: lectura de memoria slab (out-of-bounds read de metadatos), potencial DoS por corrupción de memoria.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Filter Network Traffic Vulnerability Scanning Privileged Account Management Network Segmentation Limit Access to Resource Over Network Application Isolation and Sandboxing

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Linux — Linux Kernel^AI

Referencias

JSON original (NVD)

Mostrar

{
  "id": "CVE-2026-89492",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 9.8,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "9b7895efac906d66d19856194e1ba61f37e231a4",
              "lessThan": "5e661f55ca8568471fce558effe81cca112f5cb2",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "9b7895efac906d66d19856194e1ba61f37e231a4",
              "lessThan": "fcfcba8fe17dbf2c8805690b8cc25e32d81249a4",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "9b7895efac906d66d19856194e1ba61f37e231a4",
              "lessThan": "b8a5c0c32df2c5b685ceef76ac77e37c7e1dc3ed",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "9b7895efac906d66d19856194e1ba61f37e231a4",
              "lessThan": "bc70726ddad53c7e9a9a85915bf2415b0d4f42f9",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "fs/ocfs2/dir.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.30"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "2.6.30",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.51",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/ocfs2/dir.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-09-11T20:19:31.090",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/5e661f55ca8568471fce558effe81cca112f5cb2",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/b8a5c0c32df2c5b685ceef76ac77e37c7e1dc3ed",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/bc70726ddad53c7e9a9a85915bf2415b0d4f42f9",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/fcfcba8fe17dbf2c8805690b8cc25e32d81249a4",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2: validate directory-index entry counts when reading metadata\n\nocfs2_validate_dx_leaf() and ocfs2_validate_dx_root() check the ECC and\nsignature of an indexed-directory block before it reaches higher-level\ncallers, but neither validator bounds the ocfs2_dx_entry_list counts\nagainst the capacity of the block that holds them.\n\nocfs2_dx_dir_search() then walks\n\n\tfor (i = 0; i < le16_to_cpu(entry_list->de_num_used); i++)\n\t\tdx_entry = &entry_list->de_entries[i];\n\nover de_num_used entries with no bounds check.  entry_list is either\ndx_leaf->dl_list (from ocfs2_read_dx_leaf) or, for an inline root,\ndx_root->dr_entries.  A crafted on-disk image can set de_num_used (and\nde_count, which is the __counted_by_le() bound of de_entries) to 0xffff\nand make the walk read far past the end of the 4KB metadata block, giving\na slab out-of-bounds read reachable from any path lookup, stat() or open()\non an indexed directory once the image is mounted.\n\nCommit 775c17386a6f (\"ocfs2: validate dx_root extent list fields during\nblock read\") already bounds dr_list for the non-inline dx_root, but left\nthe inline dr_entries path and the dx_leaf dl_list unchecked.  Add the\nsame read-time validation for both entry lists: de_count must equal the\ncapacity of the block (ocfs2_dx_entries_per_leaf()/per_root()) and\nde_num_used must not exceed de_count, rejecting corrupted metadata with\n-EFSCORRUPTED before ocfs2_dx_dir_search() can walk an out-of-range entry\narray.\n\nde_count is always written as exactly the block capacity when a leaf or\ninline root is formatted, so the equality check does not reject any valid\nimage.\n\nFound by 0sec automated security-research tooling (https://0sec.ai)."
    }
  ],
  "lastModified": "2026-09-21T14:17:22.547",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}