CVE-2026-74343

Estado: RecibidaAlta (7.8)—

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

kernfs: fix xattr race condition with multiple superblocks

Multiple superblocks with different namespaces can share the same kernfs_node when kernfs_test_super() finds a matching root but different namespace. This means multiple inodes from different superblocks can reference the same kernfs_node->iattr->xattrs structure.

The VFS layer only holds per-inode locks during xattr operations, which is insufficient to serialize concurrent xattr modifications on the shared kernfs_node. This can lead to race conditions in simple_xattr_set() where the lookup->replace/remove sequence is not atomic with respect to operations from other superblocks.

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Fix this by protecting xattr operations with the existing hashed kernfs_locks->open_file_mutex[] array, which is already used to protect per-node open file data. The hashed mutex array provides scalable per-node serialization (scaled by CPU count, up to 1024 locks on 32+ CPU systems) with zero memory overhead.

Changes: - Rename open_file_mutex[] to node_mutex[] to reflect dual purpose - Add kernfs_node_lock_ptr() and kernfs_node_lock() helpers - Protect simple_xattr_set() calls in kernfs_xattr_set() and kernfs_vfs_user_xattr_set() with the hashed mutex - Update file.c to use new helpers via compatibility wrappers - Update documentation to explain the extended lock usage

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 7.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.17%
Percentil entre todas las CVEs puntuadas: 5
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.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation85 %
Impacto principalT1565.001 Stored Data Manipulationimpact75 %
Impacto secundarioT1499.004 Application or System Exploitationimpact60 %

Vulnerabilidad local (AV:L/PR:L) en kernel Linux que permite a usuario local no privilegiado explotar condición de carrera en xattr para modificar datos compartidos o causar denegación de servicio.

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

Threat Intelligence Program Restrict File and Directory Permissions Remote Data Storage Filter Network Traffic Execution Prevention Encrypt Sensitive Information

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)

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{
  "id": "CVE-2026-74343",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 1.8
      }
    ]
  },
  "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": "b32c4a213698ab351b44da2fd1b2a5976c7fa033",
              "lessThan": "bf53db51359939755084d08156684ed649489592",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "b32c4a213698ab351b44da2fd1b2a5976c7fa033",
              "lessThan": "6a07814ff643b5c8e1353d8c6229f52fde205cde",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "fs/kernfs/file.c",
            "fs/kernfs/inode.c",
            "fs/kernfs/kernfs-internal.h",
            "fs/kernfs/mount.c",
            "include/linux/kernfs.h"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.1"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "7.1",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/kernfs/file.c",
            "fs/kernfs/inode.c",
            "fs/kernfs/kernfs-internal.h",
            "fs/kernfs/mount.c",
            "include/linux/kernfs.h"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-15T06:22:35.370",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/6a07814ff643b5c8e1353d8c6229f52fde205cde",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/bf53db51359939755084d08156684ed649489592",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nkernfs: fix xattr race condition with multiple superblocks\n\nMultiple superblocks with different namespaces can share the same\nkernfs_node when kernfs_test_super() finds a matching root but\ndifferent namespace. This means multiple inodes from different\nsuperblocks can reference the same kernfs_node->iattr->xattrs\nstructure.\n\nThe VFS layer only holds per-inode locks during xattr operations,\nwhich is insufficient to serialize concurrent xattr modifications on\nthe shared kernfs_node. This can lead to race conditions in\nsimple_xattr_set() where the lookup->replace/remove sequence is not\natomic with respect to operations from other superblocks.\n\nFix this by protecting xattr operations with the existing hashed\nkernfs_locks->open_file_mutex[] array, which is already used to\nprotect per-node open file data. The hashed mutex array provides\nscalable per-node serialization (scaled by CPU count, up to 1024 locks\non 32+ CPU systems) with zero memory overhead.\n\nChanges:\n- Rename open_file_mutex[] to node_mutex[] to reflect dual purpose\n- Add kernfs_node_lock_ptr() and kernfs_node_lock() helpers\n- Protect simple_xattr_set() calls in kernfs_xattr_set() and\n  kernfs_vfs_user_xattr_set() with the hashed mutex\n- Update file.c to use new helpers via compatibility wrappers\n- Update documentation to explain the extended lock usage"
    }
  ],
  "lastModified": "2026-08-17T06:19:28.850",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}