Vulnerability-Lookup

GHSA-F4X6-G3J5-68GM

Vulnerability from github – Published: 2026-05-08 15:31 – Updated: 2026-05-15 18:30

Details

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.

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

Severity

5.5 (Medium)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-43364"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-476"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-08T15:16:47Z",
    "severity": "MODERATE"
  },
  "details": "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-\u003eub_disk via\nset_capacity_and_notify() without checking if it is NULL.\n\nub-\u003eub_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-\u003eub_disk under ub-\u003emutex before dereferencing\nit, and returning -ENODEV if the disk is not available.",
  "id": "GHSA-f4x6-g3j5-68gm",
  "modified": "2026-05-15T18:30:30Z",
  "published": "2026-05-08T15:31:26Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43364"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/25966fc097691e5c925ad080f64a2f19c5fd940a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c28d945bfa92e15147e93b73f95345b9bec979b0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f13fe6794726755a43090cb680c4c58cea6aa5f1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-43364 (GCVE-0-2026-43364)

Vulnerability from cvelistv5 – Published: 2026-05-08 14:21 – Updated: 2026-05-11 22:23

Title

ublk: fix NULL pointer dereference in ublk_ctrl_set_size()

Summary

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

Severity

No CVSS data available.

Assigner

Linux

References

3 references

URL	Tags
https://git.kernel.org/stable/c/f13fe6794726755a4…
https://git.kernel.org/stable/c/c28d945bfa92e1514…
https://git.kernel.org/stable/c/25966fc097691e5c9…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 98b995660bff011d8e00af03abd74ac7d1ac1390 , < f13fe6794726755a43090cb680c4c58cea6aa5f1 (git) Affected: 98b995660bff011d8e00af03abd74ac7d1ac1390 , < c28d945bfa92e15147e93b73f95345b9bec979b0 (git) Affected: 98b995660bff011d8e00af03abd74ac7d1ac1390 , < 25966fc097691e5c925ad080f64a2f19c5fd940a (git)
Linux	Linux	Affected: 6.16 Unaffected: 0 , < 6.16 (semver) Unaffected: 6.18.20 , ≤ 6.18.* (semver) Unaffected: 6.19.9 , ≤ 6.19.* (semver) Unaffected: 7.0 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/block/ublk_drv.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f13fe6794726755a43090cb680c4c58cea6aa5f1",
              "status": "affected",
              "version": "98b995660bff011d8e00af03abd74ac7d1ac1390",
              "versionType": "git"
            },
            {
              "lessThan": "c28d945bfa92e15147e93b73f95345b9bec979b0",
              "status": "affected",
              "version": "98b995660bff011d8e00af03abd74ac7d1ac1390",
              "versionType": "git"
            },
            {
              "lessThan": "25966fc097691e5c925ad080f64a2f19c5fd940a",
              "status": "affected",
              "version": "98b995660bff011d8e00af03abd74ac7d1ac1390",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/block/ublk_drv.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.16"
            },
            {
              "lessThan": "6.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.20",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.20",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.9",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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-\u003eub_disk via\nset_capacity_and_notify() without checking if it is NULL.\n\nub-\u003eub_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-\u003eub_disk under ub-\u003emutex before dereferencing\nit, and returning -ENODEV if the disk is not available."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-11T22:23:09.555Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f13fe6794726755a43090cb680c4c58cea6aa5f1"
        },
        {
          "url": "https://git.kernel.org/stable/c/c28d945bfa92e15147e93b73f95345b9bec979b0"
        },
        {
          "url": "https://git.kernel.org/stable/c/25966fc097691e5c925ad080f64a2f19c5fd940a"
        }
      ],
      "title": "ublk: fix NULL pointer dereference in ublk_ctrl_set_size()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43364",
    "datePublished": "2026-05-08T14:21:17.654Z",
    "dateReserved": "2026-05-01T14:12:56.005Z",
    "dateUpdated": "2026-05-11T22:23:09.555Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

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GHSA-F4X6-G3J5-68GM

CVE-2026-43364 (GCVE-0-2026-43364)

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Sightings

Nomenclature