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CVE-2026-74321

Estado: RecibidaAlta (7.5)—

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

btrfs: fix invalid pointer dereference in __btrfs_run_delayed_refs()

In the beginning of the loop, we try to obtain a locked delayed ref head, if 'locked_ref' is currently NULL, by calling btrfs_select_ref_head(), which can return an error pointer. If the error pointer is -EAGAIN we do a continue and go back to the beginning of the loop, which will not try again to call btrfs_select_ref_head() since 'locked_ref' is no longer NULL but it's ERR_PTR(-EAGAIN), and then we do:

against a ERR_PTR(-EAGAIN) value, generating an invalid pointer dereference.

Leer descripción completaMostrar menos

Fix this by ensuring that 'locked_ref' is set to NULL when btrfs_select_ref_head() returns ERR_PTR(-EAGAIN) and incrementing 'count' as well, to prevent infinite looping. We do this by doing a goto to the bottom of the loop that already sets 'locked_ref' to NULL and does a cond_resched(), with an increment to 'count' right before the goto. These measures were in place before the refactoring in commit 0110a4c43451 ("btrfs: refactor __btrfs_run_delayed_refs loop") but were unintentionally lost afterwards.

Detalles técnicos trazas, registros y código del informe original
   spin_lock(&locked_ref->lock);

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 remota de kernel Linux (AV:N, PR:N, UI:N) que causa denegación de servicio por desreferencia de puntero inválido. Vector CVSS indica disponibilidad afectada (A:H) sin requerir autenticación ni interacción.

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 TrafficVulnerability ScanningPrivileged Account ManagementNetwork SegmentationLimit Access to Resource Over NetworkApplication 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 KernelAI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-74321",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.5,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "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": "0110a4c43451533de1ea1bbdc57b5d452f9d8b25",
              "lessThan": "c372ca227e16bace86f1df1fa4ae6849e2fcfa28",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "0110a4c43451533de1ea1bbdc57b5d452f9d8b25",
              "lessThan": "a71143590ce9764dbcb47617647592ff8b4d48bc",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "0110a4c43451533de1ea1bbdc57b5d452f9d8b25",
              "lessThan": "65770111a2d47c2b15e20b2ba92bb12198f289d4",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "0110a4c43451533de1ea1bbdc57b5d452f9d8b25",
              "lessThan": "015dc4a1e0c2cba551d4620eba13d26d5081dc34",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "0110a4c43451533de1ea1bbdc57b5d452f9d8b25",
              "lessThan": "ba9fa2ff5981589bb49094d3358c339b37c47f53",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "0110a4c43451533de1ea1bbdc57b5d452f9d8b25",
              "lessThan": "3b15d02be05e74321adb1e0ae0cb4ccfba7c6cb1",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "0110a4c43451533de1ea1bbdc57b5d452f9d8b25",
              "lessThan": "9faa6b69ad73f03c7bde53e07d75a28822dc9a1a",
              "versionType": "git"
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            {
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              "lessThan": "486f8298b6188ff11ef1f4be7f1d5d2e4d1b1fae",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "fs/btrfs/extent-tree.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.20"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "4.20",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.10.261",
              "versionType": "semver",
              "lessThanOrEqual": "5.10.*"
            },
            {
              "status": "unaffected",
              "version": "5.15.212",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "status": "unaffected",
              "version": "6.1.178",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/btrfs/extent-tree.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-15T06:22:32.600",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/015dc4a1e0c2cba551d4620eba13d26d5081dc34",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/3b15d02be05e74321adb1e0ae0cb4ccfba7c6cb1",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/486f8298b6188ff11ef1f4be7f1d5d2e4d1b1fae",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/65770111a2d47c2b15e20b2ba92bb12198f289d4",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/9faa6b69ad73f03c7bde53e07d75a28822dc9a1a",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/a71143590ce9764dbcb47617647592ff8b4d48bc",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/ba9fa2ff5981589bb49094d3358c339b37c47f53",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/c372ca227e16bace86f1df1fa4ae6849e2fcfa28",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix invalid pointer dereference in __btrfs_run_delayed_refs()\n\nIn the beginning of the loop, we try to obtain a locked delayed ref head,\nif 'locked_ref' is currently NULL, by calling btrfs_select_ref_head(),\nwhich can return an error pointer. If the error pointer is -EAGAIN we do\na continue and go back to the beginning of the loop, which will not try\nagain to call btrfs_select_ref_head() since 'locked_ref' is no longer\nNULL but it's ERR_PTR(-EAGAIN), and then we do:\n\n   spin_lock(&locked_ref->lock);\n\nagainst a ERR_PTR(-EAGAIN) value, generating an invalid pointer\ndereference.\n\nFix this by ensuring that 'locked_ref' is set to NULL when\nbtrfs_select_ref_head() returns ERR_PTR(-EAGAIN) and incrementing 'count'\nas well, to prevent infinite looping. We do this by doing a goto to the\nbottom of the loop that already sets 'locked_ref' to NULL and does a\ncond_resched(), with an increment to 'count' right before the goto.\nThese measures were in place before the refactoring in commit 0110a4c43451\n(\"btrfs: refactor __btrfs_run_delayed_refs loop\") but were unintentionally\nlost afterwards."
    }
  ],
  "lastModified": "2026-08-17T06:19:26.520",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}