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CVE-2026-68442

Estado: RecibidaAlta (7.8)—

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

btrfs: don't propagate EXTENT_FLAG_LOGGING to split extent maps

When btrfs_drop_extent_map_range() splits an extent map, the new split maps inherit the original map's flags through a local 'flags' variable. Commit f86f7a75e2fb ("btrfs: use the flags of an extent map to identify the compression type") changed the EXTENT_FLAG_LOGGING clearing to operate on em->flags instead of that local 'flags' copy, so a split of an extent map that is currently being logged wrongly inherits EXTENT_FLAG_LOGGING.

The flag is then never cleared on the split, and when it is freed while still on the inode's modified_extents list (for example by the extent map shrinker) it trips the WARN_ON(!list_empty(&em->list)) in btrfs_free_extent_map() and leads to a use-after-free.

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Clear EXTENT_FLAG_LOGGING from the local 'flags' copy used for the splits and only clear EXTENT_FLAG_PINNED from em->flags, restoring the behaviour prior to f86f7a75e2fb.

CVSS

Probabilidad de explotación (EPSS)

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.

Vulnerabilidad local de privilege escalation en kernel Linux (AV:L, PR:L) que causa use-after-free y crash (DoS); requiere acceso local con permisos limitados.

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

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Tecnologías afectadas (1)

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

Linux — Linux KernelAI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-68442",
  "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": "f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9",
              "lessThan": "2a9246a424f45f33a1b8367052611ebe874868ad",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9",
              "lessThan": "9304713b70e7e1450e3a76e758836fe5391bfa95",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9",
              "lessThan": "0e465c63f103a5ce6849614d6bda048d70eebec8",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "f86f7a75e2fb5fd7d31d00eab8a392f97ba42ce9",
              "lessThan": "5eff4d5b17fa1950e80bfd1ba43dc0699e61a644",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "fs/btrfs/extent_map.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.8"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.8",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.12.101",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.42",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.1.6",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/btrfs/extent_map.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-12T00:17:44.477",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/0e465c63f103a5ce6849614d6bda048d70eebec8",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/2a9246a424f45f33a1b8367052611ebe874868ad",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/5eff4d5b17fa1950e80bfd1ba43dc0699e61a644",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/9304713b70e7e1450e3a76e758836fe5391bfa95",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: don't propagate EXTENT_FLAG_LOGGING to split extent maps\n\nWhen btrfs_drop_extent_map_range() splits an extent map, the new split\nmaps inherit the original map's flags through a local 'flags' variable.\nCommit f86f7a75e2fb (\"btrfs: use the flags of an extent map to identify\nthe compression type\") changed the EXTENT_FLAG_LOGGING clearing to\noperate on em->flags instead of that local 'flags' copy, so a split of\nan extent map that is currently being logged wrongly inherits\nEXTENT_FLAG_LOGGING.\n\nThe flag is then never cleared on the split, and when it is freed while\nstill on the inode's modified_extents list (for example by the extent\nmap shrinker) it trips the WARN_ON(!list_empty(&em->list)) in\nbtrfs_free_extent_map() and leads to a use-after-free.\n\nClear EXTENT_FLAG_LOGGING from the local 'flags' copy used for the\nsplits and only clear EXTENT_FLAG_PINNED from em->flags, restoring the\nbehaviour prior to f86f7a75e2fb."
    }
  ],
  "lastModified": "2026-08-17T06:17:53.260",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}