GHSA-HM7G-G733-G35G

Vulnerability from github – Published: 2026-01-23 18:31 – Updated: 2026-02-26 18:31
VLAI
Details

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

ublk: fix use-after-free in ublk_partition_scan_work

A race condition exists between the async partition scan work and device teardown that can lead to a use-after-free of ub->ub_disk:

  1. ublk_ctrl_start_dev() schedules partition_scan_work after add_disk()
  2. ublk_stop_dev() calls ublk_stop_dev_unlocked() which does:
  3. del_gendisk(ub->ub_disk)
  4. ublk_detach_disk() sets ub->ub_disk = NULL
  5. put_disk() which may free the disk
  6. The worker ublk_partition_scan_work() then dereferences ub->ub_disk leading to UAF

Fix this by using ublk_get_disk()/ublk_put_disk() in the worker to hold a reference to the disk during the partition scan. The spinlock in ublk_get_disk() synchronizes with ublk_detach_disk() ensuring the worker either gets a valid reference or sees NULL and exits early.

Also change flush_work() to cancel_work_sync() to avoid running the partition scan work unnecessarily when the disk is already detached.

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-22995"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-01-23T16:15:55Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nublk: fix use-after-free in ublk_partition_scan_work\n\nA race condition exists between the async partition scan work and device\nteardown that can lead to a use-after-free of ub-\u003eub_disk:\n\n1. ublk_ctrl_start_dev() schedules partition_scan_work after add_disk()\n2. ublk_stop_dev() calls ublk_stop_dev_unlocked() which does:\n   - del_gendisk(ub-\u003eub_disk)\n   - ublk_detach_disk() sets ub-\u003eub_disk = NULL\n   - put_disk() which may free the disk\n3. The worker ublk_partition_scan_work() then dereferences ub-\u003eub_disk\n   leading to UAF\n\nFix this by using ublk_get_disk()/ublk_put_disk() in the worker to hold\na reference to the disk during the partition scan. The spinlock in\nublk_get_disk() synchronizes with ublk_detach_disk() ensuring the worker\neither gets a valid reference or sees NULL and exits early.\n\nAlso change flush_work() to cancel_work_sync() to avoid running the\npartition scan work unnecessarily when the disk is already detached.",
  "id": "GHSA-hm7g-g733-g35g",
  "modified": "2026-02-26T18:31:35Z",
  "published": "2026-01-23T18:31:29Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-22995"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/72e28774e9644c2bdbb4920842fbf77103a15a85"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f0d385f6689f37a2828c686fb279121df006b4cb"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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