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CVE-2026-43364

Estado: AnalizadaMedia (5.5)—

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

ublk: fix NULL pointer dereference in ublk_ctrl_set_size()

ublk_ctrl_set_size() unconditionally dereferences ub->ub_disk via set_capacity_and_notify() without checking if it is NULL.

ub->ub_disk is NULL before UBLK_CMD_START_DEV completes (it is only assigned in ublk_ctrl_start_dev()) and after UBLK_CMD_STOP_DEV runs (ublk_detach_disk() sets it to NULL). Since the UBLK_CMD_UPDATE_SIZE handler performs no state validation, a user can trigger a NULL pointer dereference by sending UPDATE_SIZE to a device that has been added but not yet started, or one that has been stopped.

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Fix this by checking ub->ub_disk under ub->mutex before dereferencing it, and returning -ENODEV if the disk is not available.

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).

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-43364",
  "cveTags": [],
  "metrics": {
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        "type": "Primary",
        "source": "nvd@nist.gov",
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          "version": "3.1",
          "baseScore": 5.5,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 1.8
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          "product": "Linux",
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          ],
          "programFiles": [
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          "defaultStatus": "affected"
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  "published": "2026-05-08T15:16:47.383",
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      "url": "https://git.kernel.org/stable/c/25966fc097691e5c925ad080f64a2f19c5fd940a",
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-476"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nublk: fix NULL pointer dereference in ublk_ctrl_set_size()\n\nublk_ctrl_set_size() unconditionally dereferences ub->ub_disk via\nset_capacity_and_notify() without checking if it is NULL.\n\nub->ub_disk is NULL before UBLK_CMD_START_DEV completes (it is only\nassigned in ublk_ctrl_start_dev()) and after UBLK_CMD_STOP_DEV runs\n(ublk_detach_disk() sets it to NULL). Since the UBLK_CMD_UPDATE_SIZE\nhandler performs no state validation, a user can trigger a NULL pointer\ndereference by sending UPDATE_SIZE to a device that has been added but\nnot yet started, or one that has been stopped.\n\nFix this by checking ub->ub_disk under ub->mutex before dereferencing\nit, and returning -ENODEV if the disk is not available."
    }
  ],
  "lastModified": "2026-06-17T10:49:27.607",
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}